Hadith are the Prophetic words and Sunnah are the Prophet's actions. Alongside memorizing and writing the Quran, many companions of Prophet Muhammad ﷺ memorized and copied his hadith and sunnah in to writing format, especially those that had very close interactions with him and spent more time with his blessed personality. The companions memorized and collected the Prophetic traditions when accompanying him, and after his passing away learned those that were missed from other more learned companions.
The collection of Abu Bakr (r.a)
According to Ayesha (r.a), Abu Bakr (r.a) had originally a collection of over five hundred traditions, and he deposited the compilation with her for custody. Ayesha (r.a) relates that one night she noticed that Abu Bakr (r.a) felt very restless. He tossed about in the bed, and could not sleep. Ayesha (r.a) got worried whether he was suffering or was worried. He made no reply, but remained restless throughout the night. The following morning he asked Ayesha (r.a) to bring him the collections that he had deposited with her. She brought the compilation and he set fire to it. On the inquiry of Ayesha (r.a), Abu Bakr (r.a) explained his conduct: "The collection contained many traditions that I had heard from other people. I thought that if I died and left behind traditions accepted by me as sahih (authentic), but really not so, then I would have to answer for that." Thus Abu Bakr (r.a) collected himself and in fact did not condemn in any way this act of collecting traditions but burned them only due to fear of personal accountability before Allah ﷻ, if even one of them resulted in being incorrect. Therefore its not the collection he disliked but his personal accountability due to deep consciousness of Allah ﷻ that he feared.
Hadith collection during Umar's rule
It was during his rule that Umar (r.a) laid the foundation for the practice of ilm al hadith (science of hadith), process used for the hadith preservation by subsequent generations of Islamic scholars. The practice with Umar (r.a) was that if any new problem cropped up, he announced the issue in the public assembly, and inquired if any of them remembered any tradition of the Holy Prophet ﷺ on the subject. Those who narrated any tradition were required to produce some witnesses in support of the tradition. If such statement was duly corroborated and was in accordance with the spirit of the Quran as well as common sense it was adopted and applied to the facts of the case in hand. In this way a rich corpus of Hadith was built up. To read more on the agreed principles for acceptance of a hadith in his era please read: What is Ilm Al Hadith (Science of Hadith).
Hadith collections by prominent sahabas (companions)
Its stated the Abu Ayyub Ansari (r.a), the famous Ansari companion, traveled for a month’s journey to Egypt listen to a hadith of the Prophet ﷺ directly from its narrator Uqba ibn Amir (r.a) who said that Prophet ﷺ said: “Whoever cover the faults of the believer Allah will cover his faults on Judgment day.” (Bukhari & Muslim). After hearing he did not even change his saddle of the horse and immediately left to come back. Jabir bin Abdullah (r.a) went a month’s journey from Madinah to Syria to secure authenticity of a tradition from Abdullah ibn Amr (r.a) as Abdullah used to himself write hadith. Abdullah (r.a) reports: "I used to write everything i heard from the Messenger (saw) as i wanted to Preserve it. The Quraish forbade me, saying "Do you write down everything that you hear (from him) and The Messenger ﷺ is a human being who sometimes speaks in anger and joy? (that is that he may say something emotionally that may not be worth writing)." So I stopped. Then i mentioned this to Allah's Messenger ﷺ. He pointed with his finger to his mouth and said "Write! By the One in Whose Hand is My Life! Nothing comes out of it (His Mouth) except the Truth!" 
Said ibn Al Musayyib (r.a) used to travel days and nights to listen to a single hadith from its original narrator. It is on record that companions like Ali ibn Abi Talib (r.a), Abu Huraria (r.a) and other companions collected their own sahifa (scripture) of Prophetic Hadith such as:
Sahifah (scripture) of Ali ibn Abu Talib (r.a)
Sahifah of Abdullah ibn Abi Auf (r.a)
Nuskah of Samurah Jundab (r.a)
Kitab of Abu Huraira (r.a)
Sahifah of Jabir Bin Abdullah (r.a) 
It was these books from which was derived most of the hadith literature later found in the authentic collections that we famously know today as Bukhari, Muslim, Abu Dawud, Ibn Majah, Tirmidhi etc.
 Masud-ul-Hasan, Professor. 1982. "Khalifa Abu Bakr - Mushaf, Hadith, Tasawwuf, Fiqh, and Poetry." Alim - The world's most useful Islamic software. Accessed 03 05, 2019. http://www.alim.org/library/biography/khalifa/content/KAB/16/2. (Masud-ul-Hasan 1982)
 Sunan Abu Daud of Imam Abu Daud, Hadith #3161
 Kazi, Mazhar. April 1, 2007. Guidance from Hadith & Sunnah. Al-Huda Publications - (Kazi April 1, 2007)
Define Ilm Al Hadith (Science of Hadith)
Ilm al hadith means Science of Hadith, which refers to the Knowledge of the scrutiny of hadith literature. Basically every hadith has a chain (isnad) of narrators that are going all the way back to the Prophet ﷺ. Studying biography of each narrator in a chain who transmits the hadith, in addition to comparing it with other chains of that same hadith, if any, including studying linguists of text as well as circumstances involved when particular hadith was narrated and others factors involved in recording are all included in the subject of ilm al hadith. There exists a few common misconceptions that the collection of hadith took place many years, in most cases 200 years, after the Prophet's death or that its initial collection was started by the students of the companions, and Prophet Muhammad ﷺ and his companions never supported or indulged in this activity. Such misconceptions are false because there is evidence that hadith were being collected during the Prophet's life (discussed in subsequent posts) and in fact the foundation and practice of Ilm Al hadith (Science of Hadith) was initiated by his companions, in a more organized manner especially during the rule of Umar ibn Khattab (r.a), the 2nd successor of Prophet Muhammad ﷺ.
Foundation of Ilm Al Hadith (Science of Hadith)
Umar (r.a) was the first to realize the necessity of the proper sifting of the hadith narrations. Those who narrated any hadith were required to produce some witnesses in support of the tradition. In this way a rich corpus of Hadith was built up. Umar (r.a) classified the traditions in two broad categories. One category of traditions pertained to religious, moral and social affairs pertaining to the community at large. The other traditions revolved round the person of the Holy Prophet ﷺ and pertained to his words and deeds as a human being i.e. the Prophet's Sunnah. Umar (r.a) distinguished between these two categories. All matters falling in the first category were binding and had the status of law. Umar (r.a) evolved the following principles on the basis of which the traditions were to be accepted:
(1) The report should be literally faithful;
(2) Every Hadith narrated should carry with it the name of the narrator and the chain of narrators;
(3) The narrators must be men of proven faith and integrity;
(4) In judging the veracity of a report the occasion and circumstances involved should be taken into consideration;
(5) The report should not be repugnant to the Holy Quran;
(6) The report should be rational.
Subsequent Developments in Ilm Al hadith (Science of Hadith)
By the end of 1st century Hijrah (100 AH - 720 CE) majority Companions passed away leaving their compilations behind including the framework and process for hadith evaluation taught to Tabi’een (their students). However this process needed to be a bit more supervised especially to avoid and separate the unauthentic traditions that began circulation in subsequent years. Therefore, during the rule of Umar bin Abdul Aziz (r.a) (717 - 720 CE), one of the Ummayad Caliphs (also known as 2nd Umar due to his piety), ordered the collection of ahadith on a large scale. He assigned learned scholars and hadith experts of Madinah such as Abu Bakr Ibn Hazam (Qadi of Madinah) and famous Ibn Shihab al-Zuhri, who were also students of Prophet's companions, Ayesha (r.a) and Anas bin Malik (r.a), expert hadith specialists and teachers. During the mid of 2nd century Hijrah (150 AH), hadith centers came to exist and scholars like Imam Malik (Died 179 AH) and Sufyan Thauri (Died - 168 AH) and several others opened their centers to teach hadith with rules as laid down by their predecessors.
In subsequent years rules of hadith collection were expanded and further conditions were added such as ilm al rijal (names of narrators and their biographies) and each hadith that included a chain (isnad) of narrators was classified based on the reliability of the narrators such as their piety, intelligence, if they were of forgetful nature, or if they were known to ever have lied. It was based on the strength of the narrators is how each hadith came to be classified with a status such as Dhaeef (weak), Sahih (authentic), Mutawattur (narrated through several chains), Hassan (good - lesser than Sahih), Ghareeb (strange due to some interruption in chain). Based on each status later compilations were made such as Sahih Bukhari and Sahih Muslim, with sahih meaning they are very authentic due to evaluation involved in their chains. One of the authors of Hadith book comments on this unique process: “Every Muhaddith (hadith expert) even today, when describes a hadith, he suffixes it with a specific name of a hadith denoting its level of authenticity (such as ‘Hassan’ or ‘Sahih’), then quotes the book of hadith where its documented (such as Musnad of Ahmad) and then prefixes it with an unbroken chain of narrators spreading over the last 1400 years through whom he received the hadith. No other religion, nation, party or even small group of people can show the parallel of what early Muslims did to ensure the authenticity of hadith and Sunnah.”
In subsequent centuries scholars studied these ahadith, added their comments to explanations given by their teachers and developed upon the wisdom and knowledge, resulting in science of Fiqh (practices/ruling) & Shariah (Islamic law). It is extremely sad to see that today many Muslims doubt the authenticity process of all hadith or some of it, without researching. And worst is that some even compare the uniquely systematic collection of this literature with collection of Christian Gospels that clearly lacked any consistent methodology and process in its compilation.
 Masud-ul-Hasan, Professor. 1982. "Khalifa bin al-Khattab - Hadith and Fiqh." Alim - The world's most useful Islamic software. Accessed 03 05, 2019. http://www.alim.org/library/biography/khalifa/content/KUM/16/1 . (Masud-ul-Hasan 1982)
 Kazi, Mazhar. April 1, 2007. Guidance from Hadith & Sunnah. Al-Huda Publications - (Kazi April 1, 2007)
Fiqh means the practices and rulings of Islam deducted by Islamic scholars from Quran and Hadith, the 2 primary sources of guidance. The need for systematization of Islamic knowledge such as Fiqh (practices and rulings) and other sciences such as ilm al hadith (sciences of hadith), Tasawwuf (science of spirituality) and all related subjects came to be developed later due the need of time.
During the Prophet's life, his example was right in front of the companions and whenever verses of Quran were revealed they were direct witnesses to it. Therefore the companions had direct access and first hand experience of the revelation process and its implementation unlike Muslims of the later centuries. They not only witnessed but also recorded them. Additionally they were a smaller community, concentrated in to one large group within the 2 major cities of Islam i.e. Makkah and Madinah. If any companion erred or forgot about a particular practice or ruling of the Prophet ﷺ, he was immediately corrected by the other who was living within the same community. After the passing away of the Prophet ﷺ, gradually Islam spread throughout the region and it accepted new people in to its fold. When new people entered Islam especially during the Rashidun period i.e. during rule of first 4 successors of Prophet Muhammad ﷺ (namely Abu Bakr (r.a), Umar (r.a), Uthman (r.a) and Ali (r.a)) the companions also spread to different regions. There they focused on the preservation of knowledge they had learned from the Prophet ﷺ and focused on teaching to the local people. This is how schools of thought came to be developed in early Islam that were named after each companions such as school of Abdullah ibn Masud (r.a) in Kufa and Abdullah ibn Umar (r.a) in Makkah, Abu Darda (r.a) in Damascus, Muadh bin Jabal (r.a) in Palestine and other companions went other places. Therefore, the people of each town had their own set of teachings they acquired from them and were satisfied.
Later on these cities were exposed to the hadith and sunnah information of the Prophet ﷺ which was taught in other cities by other companions which led towards the developing stage of various sciences such as ilm al hadith (sciences of hadith), fiqh (rulings and practices) and better understanding of Shariah (Islamic law). This also caused the need for pious among the knowledgeable to learn more by travelling to those cities which they did and compiled books and knowledge, and taught there, which then led towards development of major schools of thoughts such as 4 (Maliki, Sha'afi, Hanbali, Hanafi) and subsequent systematic compilations of hadith books. Many of these scholars that hailed from each major city of the Islamic world were all students of the teachers who themselves were students of either those learned from the Tabi'een (second generation or students of companions) or lived longer to have claimed learning directly from the companions. Therefore this is a process of traditional knowledge which has been handed down from the time of Prophet ﷺ to later generations through medium of pious and knowledgeable ones in a systematized manner.
Sacred status of hadith/sunnah in Islam
The primary sources of revelation in Islam are the Quran and Hadith/Sunnah. Quran explicitly orders the Muslims to obey and follow the Prophet's teaching and example when learning the book: "Allah did confer a great favour on the Believers when He sent among them a Messenger from among themselves, who rehearses to them the Signs of Allah, purifies them, instructs them in Scripture, and teaches them Wisdom, whereas previously they had been in plain error."  Here, and many other places in the Quran, we are informed about the importance of Hadith & Sunnah because the entire practice of the Quran and how to live by it is found in the life of the Prophet ﷺ. Since Allah ﷻ promises in ‘Al Quran 15:09’ that He has protected the message of guidance from all corruption till the day of judgment therefore His commandment to follow Prophetic teachings also hold exact same surety of protection.
The role of Isnad in hadith preservation
The hadith literature is a sacred tradition alongside Quran and the key to this sacredness lies in something called Isnad which basically means "chain of transmission". An Isnad contains a list of narrators who memorized and transmitted a hadith through a chain, that directly reaches all the way back to the sacred person of the Prophet ﷺ. For example lets say Imam Zaid memorized and wrote down a hadith he heard from his teacher Imam, who learned and memorized from his teacher a Companion, who directly met and heard from the Prophet ﷺ. Now when Imam Zaid will go and teach it to his students they will memorize the tradition, write it down and in turn will teach to their students. Through this process not only the hadith got memorized by who were taught but also transmitted from generation to generation, oral and in writing, linked with a chain that reaches back all the way to the Prophet’s sacred personality, who himself was recipient of revelation from Allah ﷻ through Angel Jibraeel (alaihi salaam). But there is one major sacred & spiritual factor guiding the isnad process. Nazim Bakhsh, quotes in his writing Shaykh Hamza Yusuf, a leading Islamic scholar, who gives an overview of how scholars have made use of Isnad process from generation to generation through something called Ijaza: "Shaykh Hamza Yusuf, has often said that isnad is the secret of this Ummah and a gift from Allah. Without isnad the entire tradition could very well collapse. The system of ijaza (teaching licenses) is intricately linked to isnad in that one takes his knowledge from noble men and women who took their knowledge from those who took their knowledge from those….all the way back to that model community (companions) and to the blessed Messenger himself, whose knowledge, without a shadow of doubt, came from the Lord of the Divine Throne through his messenger, the Angel Gibril (Gabriel), upon him be peace.”  Ijazas are teaching licenses given by a Sheikh, well versed and knowledgeable in Islam to those of his students whom he approves to be fit of transmitting hadith and other knowledge directly from himself. This has maintained the transmission process called isnad not only on the academic level but also on a spiritual level.
As discussed earlier, Isnad is part of a wider process called ilm al hadith (sciences of hadith), that maintains the unanimous position of the Islamic scholars who not only recorded & memorized the hadith but also scrutinized them making it clear which of them fall under category of sahih (authentic), mursal (interrupted), dhaeef (weak), munkar (rejected), mawdoo (fabricated), in terms of their chain of narrators. They were familiar with who the forgers were and who were the unknown narrators, who should not be considered fully trustworthy in the chain. All of that is due to the position and importance of the Prophet Muhammad ﷺ, as the seal of all the Prophets and leader of humankind. Hence it is these sacred factors that have guided the systematic process of hadith collection and preservation due to which forgeries and interpolations have not been able to be attributed to him and to be accepted by the majority consensus of Islamic scholars.
 Al Quran 3:164 - Asad Translation
 Baksh, Nazim. 2015. In The Spirit of Tradition. January 5th. Accessed January 7th, 2020. http://masud.co.uk/in-the-spirit-of-tradition/.
There has been discovery of several hadith texts belonging to the 1st Century Hijrah (Islamic year) whose contents were compared by modern Muslim & Non-Muslim scholars and researchers, with the canonical collections of the 3rd century Hijrah (9th century CE) of Imam Bukhari, Imam Muslim, Imam Ahmad etc. Their findings reveal that the hadith were almost identical with no issues. Among those that were subject to such research in the recent years in particular were Sahihfa (scriptures) of Hamam ibn Munabbih and Musannaf of Abdul Razzaq of the 1st Century. Below are some of their findings which support the fact that not only were hadith being collected in the first century but also their authenticity has been proven to be correct.
Sahifah (Scripture of) Hamam Ibn Munabbih
Sahifah (Scripture of) Hammam ibn Munabbih (d. 101 AH) is perhaps one of the earliest known hadith collections, by 8th century scholar Hammam ibn Munabbih. It has been translated in the 20th century by Muhammad Hamidullah - a world-renowned Muhaddith, Faqih and scholar of Islam and International Law from Pakistan, winner of national award Hilal-e-Imtiaz in Pakistan. Hammam ibn Munabbih was the taba'een (student) of the Companion, Abu Huraira (r.a), the famous hadith transmitter. Dr Hamidullah published this Sahifa of Hammam around 1979 and it proves that hadith were collected in the Mid 1st century Hijrah. His research was also compared by orientalists such as, by R. M. Speight who mentions that: “… the texts in Hammam and those recorded in Ibn Hanbal, Bukhari and Muslim with the same isnad show almost complete identity, except for a few omissions and interpolations which do not affect the sense of the reports. On the other hand, the same ahadith as told by other transmitters in the three collections studied show a rich variety of wording, again without changing the meaning of the reports.”  Speight shared his analysis after comparing it (i.e., the Sahifa) with about the 1500 variant readings of the same ahadith found in the collections of Ibn Hanbal (Musnad), al-Bukhari (Sahih) and Muslim (Sahih); dating from 3rd Century Hijrah.
Musannaf Abdul Razzaq
Another book from the 1st century belonging to the famous early Muslim Muhaddith (hadith expert and teacher) named Abdul Razzaq Sanani (124 AH - 211 AH) was studied by another Western Non-Muslim writer name Harald Motzki. His analysis appeared in the Journal of Near Eastern Studies and he says that: “The works of ‘Abd al-Razzak are extremely important for the study of early Islamic jurisprudence, hadith and exegesis of the Kur’an because they contain older sources or materials which have otherwise been lost. ‘Abd al-Razzak had direct access to authors of the first extensive compilations of traditions arranged according to subject . . . like those by Ma’mar b. Rashid, Ibn Djuraydj, Sufyan al-Thawri and Sufyan b. ‘Uyayna. His own Musannaf is to a large extent compiled from materials received from these four scholars, and it is very probable that these materials came for the most part from their books. In general, ‘Abd al-Razzak’s transmission from these teachers of his seems to be reliable . . . While studying the Musannaf of `Abd al-Razzaq, I came to the conclusion that the theory championed by Goldziher, Schacht, and in their footsteps, many others - myself included - which in general, reject hadith literature as a historically reliable sources for the first century AH, deprives the historical study of early Islam of an important and a useful type of source.” 
Even though as Muslim Believers we do not need the above findings to prove us the authenticity of the hadith literature, yet this confirms for us even more that the hadith of the Prophet ﷺ were collected through a science called ilm Al hadith which no doubt was an effective methodology and has produced for us results that helped Muslims guided for the past 14 centuries.
 R. M. Speight, “A Look At Variant Readings In The Hadith”, Der Islam, 2000, Band 77, Heft 1, p. 170 https://www.islamic-awareness.org/hadith/hadith
 H. Motzki, “al-Sanani, Abd al-Razzak b. Hammam b. Nafi, Abu Bakr al-Yamani al Himyari (IX 7a)”, in Encyclopaedia of Islam CD-ROM Edition v. 1.0
Originally written on July 12, 2020 on Quora - Were Persians forced into accepting Islam? Did Islam borrow its Hadith & Quran Teachings from Zoroastrianism & Persian?
Some articles online, such as this Iranica Encyclopedia article, claim that hadith were influenced by Iranian ideas and practices. Such as Prophet’s prohibition on being despondent and gloomy at someone’s loss, the Prophet’s prohibition on urinating while standing, encouraging the use of sewak or meswak which may have originated from sawaag a Persian word for the same thing. The usage of odd numbers such as 3, 7 or 33 when mentioning the amount of dhikr, the number of rakaats (prayer rounds) or multiplying of deeds etc. The Prophet’s mount for Mir’aj called Buraq may be Arabicized form of baraag or baarag “a riding beast, mount” in Persian language, and his Mi’raj is the similar experience as recorded in Book of Arda Wiraz by a Persian Prophet or religious figure named Wiraz. It is also claimed that the Prophet ﷺ must have adopted many traditions from his Persian companion named Salman Al Farsi (the Persian).
Prophet Muhammad ﷺ never prohibited being gloomy, what he prohibited was wailing, a pre-Islamic ignorant act among Arabs was wailing and beating when in grief: “beware of the devil’s croaking! As long as it comes from the eye and the heart, it is coming from mercy; and as long as it comes from the tongue and the hand, it is coming from Satan.” (Narrated from Ibn `Abbas by al-Bayhaqi in al-Sunan al-Kubra) The Prophet ﷺ prohibited his Ummah to urinate while standing but he also urinated in a very unclean place standing which made sense to avoid dirtying his clothes. (Sahih al-Bukhari 2471) The meswak or sewak, tooth stick introduced by the Prophet ﷺ cannot be the Persian use of sawag because the use of meswak led towards a victory of Muslims in the battle against the Persian army. The book, Healing Body & Soul by Amira Ayad tells that Saad bin Abi Waqas (r.a), the army general and victor against Persian battles noticed that the Muslims were being defeated continuously. After evaluation he concluded that the Muslims had forgotten the Sunnah of meswak. He immediately ordered the Muslims to use meswak and ask Allah ﷻ for forgiveness. The Persian spies in the Muslim camps saw the entire army using meswak thought that they were sharpening their teeth for cannibalism which spread fear among the Persians and they were routed. This shows meswak may not have been a Persian tradition. As for the usage of odd numbers like 3, 7 or 33, the Prophet Muhammad ﷺ stressed this fact because the Quran stresses on this fact: (Al Quran 89:1) “By the dawn and the even and the odd.” The even is the creation and the odd is Allah ﷻ because every even number is divisible such as 2, 4, 6, 8, but every odd is indivisible such as 1, 3, 5, 7, the even is creation that has pairs and opposites while Allah ﷻ is unique and without pairs. This is not a Persian tradition I believe, its a philosophy of the Quran about Allah ﷻ and His creation. As for barag in Persian that means “a riding beast or mount” cannot be equivalent to Buraq in Arabic because this term was not in use among Arabs for any riding beast. Prophet Muhammad ﷺ used this term for the supernatural conveyance. Buraq was a special animal of a special kind because buraq is derivative of root barq which means “intense” and “bright lightning” while Persian term does not carry the same meaning. On the other hand the Persian literature called Book of Arda Wiraz where Wiraz, supposedly a Persian Prophet, gave details of his dream journey where he saw insight in to hell, paradise and communicated with Ahura Mazda (Allah). The book is actually compiled in 9th and 10th Century CE during Islamic period, hence it could possibly have been influenced by traditions of Mir’aj. But even if this dream journey was authentic and pre-Islamic then Prophet’s of Allah ﷻ have received divine insight in to hell, paradise, day of judgment etc. But if one notices the details of the Mir’aj they conform to a physical journey experience than a dream, Prophet Muhammad ﷺ had never traveled to Jerusalem, yet, to the amazement of disbelievers, gave the correct details of city, traveling caravans and places in between. In fact even in our times many recent scientific & astronomical findings explain the Prophet’s Mir’aj as well, please read the following writing:
The Night Journey & Ascension - When Allah ﷻ Tested the Believers & the Disbelievers
Did Prophet Muhammad ﷺ Ever Travel To Jerusalem Before The Night Journey?
Scientific Viewpoint of the Night Journey & Ascension.
Additionally there may be some misconception among certain Western academia, or others who hold the belief that the Salaah (5 times prayers) comes from pre-Islamic Persian tradition. What many forget is that initially prayers in Islam were 50 and were reduced to 5. At one point they were only 2, then increased to 5. As for Salman Farsi (r.a), he converted to Islam at the blessed hands of Prophet Muhammad ﷺ during his prophet hood in the city of Madinah. Salman (r.a) was not present during first 13 years of the Prophet's mission in Makkah and this can be confirmed from all historical sources that mention the story of Salman (r.a) such as Salman the Persian. In fact during the Prophet's mission in Makkah there was no Persians that resided in the town and there was no influence of Zoroastrianism whatsoever.
1. HADITH v. AS INFLUENCED BY IRANIAN IDEAS AND PRACTICES - https://iranicaonline.org/articles/hadith-v
2. Ayad, Amira, and Jamila Hakam. Healing Body & Soul: Your Guide to Holistic Wellbeing following Islamic Teachings. pgs. 443-44
4. Salman The Persian - https://en.wikipedia.org/wiki/Salman_the_Persian
5. Pic taken from https://www.ames.cam.ac.uk/12th-century-fatimid-tiraz