What is Halaal (Permissible) & What is Haraam (Forbidden) in Islam?
Allah ﷻ says in the Quran: “Say: Lawful to you are all the good things of life (at-tayyibat)…”. Muhammad Asad comments on this verse: “The implication is, firstly, that what has been forbidden does not belong to the category of "the good things of life" (at-tayyibat), and, secondly, that all that has not been expressly forbidden is allowed. It is to be noted that the Qur'an forbids only those things or actions which are injurious to man physically, morally or socially.” What has been explicitly forbidden in Islam is clearly mentioned in the Quran and the prophetic hadith, the two major sources of guidance in Islam. Hence, everything is halaal (legal) in Islam except what has been explicitly declared haram (illegal). Allah ﷻ further elaborates in the same Surah on the good things of life (at-tayyibat) that provides insight how we should act even in regards to the permissible: “O YOU who have attained to faith! Do not deprive yourselves of the good things of life, which God has made lawful to you, but do not transgress the bounds of what is right: verily, God does not love those who transgress the bounds of what is right. Thus, partake of the lawful, good things which God grants you as sustenance, and be conscious of God, in whom you believe.” Chances are that overindulgence in what is halaal can be also detrimental therefore a believer needs to be careful when treading his or her path in this life within the legal boundaries as reminded to us in the wording “do not transgress the bounds of what is right” & “and be conscious of God”. Just as sugar is halaal but excess can cause diabetes or spending on oneself and others on necessary things is halaal but overspending on unnecessary makes one overindulgent. As the saying goes, “an atom of a prevention is better than tons of cure.” A believer lives best with a preventive attitude in life, which is the key to success in this world and the hereafter. This attitude is best explained in the following conversation of the Prophet’s companion Umar ibn al Khatttab (r.a): Umar (r.a) asked Ubbay ibn Kaab (r.a), “What is the meaning of Taqwa (God consciousness)?” Ubbay ibn Kaab said, “O Amir ul Mumineen (leader of the believers), have you walked on a field that had a lot of thorny plants?” Umar said, “Yes” Ubbay ibn Kaab said, “So what did you do?” Umar replied, “I lifted up my clothes and I was very careful,” Ubbay ibn Kaab said, “That is Taqwa.” This teaches that not only does a believer walk on the path within specified boundaries of halaal and make sure they do not cross them but they also remain cautious from being pricked by the thorns of overindulgence.
 Al Quran 5:04
 Asad, Muhammad. 1980. Message of the Quran - Surah Al-Ma'idah (The Repast) - The Fifth Surah. Great Britain: Dar Al-Andalus.
 Al Quran 5:87-88