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This Chapter/سورة is considered to be the summary of whole Qur'an by almost all notable classical and modern Islamic scholars including Imam Shafi, Ibn Kathir, Israr Ahmed and Farhat Hashmi.
What is Surah Al-Asr?
Ibn Kathir, a traditional exegetic holds that this sura, as a warning to believers not to waste time or they we could be humiliated or even ruined.
Imam Shafi, a jurist and traditional scholar of Islam, held-that if God had only revealed this surah it would have been sufficient for the guidance of all humankind.
It summarized the very essence of the Qur'anic message. Thus, Imam Shafi’i asserts that if one followed its counsel, it was enough for humankind to achieve success in life.
Sayyid Qutb, a modern exegete of the Qur'an, asserts that this surah outlines a complete system for human life based on an Islamic viewpoint. He says that it defines, in the clearest and most concise form, the basic concept of faith in the context of its comprehensive reality. He further says that he is gravely shocked to see the loss and ruin in which humanity finds itself. He is critical of Muslims and non-Muslims and particularly witnessing that humankind is turning away from the goodness that God has bestowed upon it. He is confident that the guidance of this surah is what made the early Muslim great as it can do for those that follow it in the long history of humanity. He says that once the early Arabs were aroused by such surahs, they quickly burst the bounds of Arabia and zealously worked toward the salvation of humanity.
Al-Tabarani: Interestingly, when humankind finds itself at a loss; it can revive itself by returning to the formula provided by the third verse and the four principles/conditions, which are adhered to as a foundation. We saw how these four principles operated on both physical and spiritual levels. This is probably the reason why the companions of the Prophet did not want to become heedless of the foundational message of Islam. Consequently, they used to meet one another and only depart until one of them recited surat-Al-Asr to the other and they bid peace upon one another.