Tasawwuf is basically the science of gaining spirituality through the use of your heart. Heart in Islam is the bridge than connects the physical side of our’s with spiritual. The heart needs continuous purification as rust of earthly distractions & ignorance tarnish it and we may not be able to fully attain the purpose of our existence. The purpose of our existence is mentioned in the following Quranic verse: (Al Quran 51:56) "And I did not create the jinn and mankind except to worship Me." In this verse the term Ibaadah in Arabic is usually translated as "worship" was understood as "knowledge" by the early Muslims such as Ibn Abbas (r.a), the cousin of the Prophet ﷺ and known as the Scholar of this ummah (Muslims). He explained the above verse as "knowledge" meaning we have been created to gain communion with Allah ﷻ and its through His knowledge that we can may live our purpose.
We have been created to know Allah ﷻ and by knowing Him will benefit us. As there is a famous Hadith Qudsi (words of Allah ﷻ) the Prophet ﷺ was told by Allah ﷻ that: "I was a hidden treasure; then I wished to become known. Then I created the creation, so that I may be known." The knowledge of Allah ﷻ is revealed only to those hearts that carry the light of Imaan (belief). The cleaner the heart and stronger ones belief is the more knowledge Allah ﷻ bestows. The Prophet ﷺ said “There is a piece of flesh inside every body, if it is good entire body will be good and that is the heart.” (hadith) As Allah ﷻ has mentioned in the Quran that those whose hearts are pure, clean and humble are the ones who will be successful on the day of judgment: [Al Quran 26:88] "The day on which property will not avail, nor sons ….Except him who comes to Allah with a heart free (from evil)."
The only thing that obstructs this heart from gaining knowledge is our Nafs (human self or base urges) also referred to as Soul in English. This Nafs has inherent tendencies which makes us have attraction towards earthly pleasures and distractions. It continuously strives to attach us to the earth and its beauties so we may deviate from our purpose of life and to the point of even forgetting our Creator. It is due to this reason why the Sufiyya or Sufis (Saints) have always emphasized on Greater Jihad (struggle) as the ultimate goal of life which is to strive against our own Nafs. This is due to a famous hadith of the Prophet ﷺ who referred to greater Jihad as “The servant’s struggle against his lust (hawah).” as opposed to lesser jihad which is fighting with arms in defense.
The Lust termed as Hawah (or Hawass in Urdu, or shahwat in Persian) is also mentioned in the Quran that our Nafs generates to pull us away from Allah ﷻ: [Al Quran 7:176] "And if We had pleased, We would certainly have exalted him thereby; but he clung to the earth and followed his low desire (Hawa)." Allah ﷻ would exalt in ranks those who strive against the influences of Nafs. Allah ﷻ has given a description of those who keep their hearts attached to Allah ﷻ and do not submit to their lust & desires and He advises the believers to follow their path: (Al Quran 18:28) "And keep yourself patient [by being] with those who call upon their Lord in the morning and the evening, seeking His countenance. And let not your eyes pass beyond them, desiring beauties of the worldly life, and do not obey one whose heart We have made heedless of Our remembrance and who follows his desire (Hawa) and whose affair is ever [in] neglect."
Allah ﷻ has praised these people who are calling upon Him morning and evening and involved in doing His Zikr (Remembrance) and He tells us elsewhere as to why their hearts are not easily distracted by worldly attachments: (Al Quran 13:28) "… and whose hearts find peace in the remembrance of God- truly it is in the remembrance of God that hearts find peace." As their hearts being at peace due to Zikr (remembrance) distractions of the Nafs and Hawa do not bother them, they are at peace with their Lord as there is another Hadith Qudsi that Prophet ﷺ told us from Allah ﷻ “Heavens and the earths cannot contain Me but within the momin’s (believers) heart I enter like a guest.” It is the effects of our Hawa which cause distractions to our Hearts that are generated from our Nafs. If we continue to fight them with Jihad (struggle) and remain stead fast then Allah ﷻ will make ways for us to gain closeness to Him so we may succeed in the purpose of life: (Al Quran 29:69) "But as for those who strive hard in Our cause (Jahaduu) - We shall most certainly guide them onto paths that lead unto Us: for, behold, God is indeed with the doers of good.
How Heart of a Mumin (believer) gains knowledge of Allah.
According to Sufi literature there is a saying from the Prophet ﷺ that Qalbu Mumin ArshAllah meaning “The heart of a Mumin (believer) is the Throne of Allah.” the throne of Allah represents His dominion and His Kingdom. Due to hearts being pure and attached to Allah ﷻ gain the spiritual access to His throne in the heavens where the knowledge of the unseen is available. This hadith points us towards the nearness these hearts gain with Allah and this is also confirmed by one of the verses of the Quran: (Al Quran 40:07) "THEY WHO BEAR [within themselves the knowledge of] the throne of [God's] almightiness, as well as all who are near it, extol their Sustainer's limitless glory and praise, and have faith in Him, and ask forgiveness for all [others] who have attained to faith: "O our Sustainer! You embrace all things within [Your] grace and knowledge: forgive, then, their sins to those who repent and follow Your path, and preserve them from suffering through the blazing fire!" (Assad Translation) Muhammad Asad in his commentary Message of the Quran translated the above verse as such based on the commentary of the great Persian scholar Imam Al-Baydawi author of Tafsir al-Baydawi. Imam Baydawi explains that "those who are near the Arsh (Throne) of Allah" are not only Angels but also those humans whose hearts are attached to Allah ﷻ:
“In his commentary on the verse which we are now considering, Baydawi states explicitly that the "bearing" of God's throne of almightiness (al-'arsh - see note 43 on 7:54) must be understood in a metaphorical sense: "Their carrying it and surrounding it [or "being near it] is a metaphor of their being mindful of it and acting in accordance there with (majaz 'an hifzihim wa tadbirihim lahu), or a metonym (kinayah) for their closeness to the Lord of the Throne, their dignity in His sight, and their being instrumental in the realization of His will." But whereas it cannot be denied that the present verse refers also to angels, it does not follow that it refers exclusively to them. In its abstract connotation, the verb hamala frequently signifies "he bore [or "took upon himself"] the responsibility [for something]": and so it is evident that it applies here not only to angels but also to all human beings who are conscious of the tremendous implications of the concept of God's almightiness, and hence feel morally responsible for translating this consciousness into the reality of their own and their fellow~beings' lives.” (Surah Al Ghafir)
Allah ﷻ says in Quran how he created the universe and He is established over His Throne from where He commands all the affairs of His creation and the knowledge of everything lies with Him. (Al Quran 10:03) "Who created the heavens and the earth in six days, then established Himself on the Throne (of His Dominion), governing all affairs of the universe …" (Al Quran 65:12) "The Command descends among them, so that you may know that Allah is powerful over every thing, and that Allah has encompassed every thing in knowledge." These hearts that keep themselves pure due to continuous struggles (jihad) against their own Nafs (human self or base desires) gain nearness and access to the assembly of Angels near the Throne of Allah from where all knowledge descends and their hearts are filled with them. Tasawwuf is that science that can assist us in achieving that.
Interesting account on the death of Sufi Shaykh Bayazid Bistami (r.a)
Once a man who lived in the town of Shaykh Bayazid Bistami(r.a) saw himself in a dream carrying the throne of Allah on his head. He was amazed when he got up and was restless in his efforts to find out why he had seen such a dream. He decided to go to the Shaykh to find out the interpretation but soon discovered that earlier today the Shaykh passed away. Feeling so sad due to news of the loss such big loss and also wondering how would he find out the true meaning of his dream. Suddenly when the funeral with the Janazah (bier or coffin) of Shaykh was being carried by people in the streets to be buried he joined the crowds and being pushed around found himself underneath the Janazah (bier) while carrying it on his head. Right at that moment he realized the interpretation of his dream and praised Allah and made abundant dua for blessings on the Shaykh. This dream explains for us as to how the heart of the Shaykh had become the Throne of Allah due to his proximity and closeness with Allah. His heart was one of those where secret knowledge of the heavens was disclosed and no doubt the life of this Saint of Islam proved that as well.
Please also read Islamic Spirituality: the forgotten revolution By Shaykh Abdul Hakim Murad ISLAMIC SPIRITUALITY: the forgotten revolution .