Ash-Shams, "The Sun," is the ninety-first surah — 15 verses revealed in Mecca.1 The Prophet ﷺ named it among the surahs suitable for leading a congregation that includes "the old, the weak and the needy."4
What it is about
The surah opens with a long chain of oaths: "By the sun and its brightness and [by] the moon when it follows it and [by] the day when it displays it and [by] the night when it covers [i.e., conceals] it," by the sky, the earth "and [by] the soul and He who proportioned it and inspired it [with discernment of] its wickedness and its righteousness." All of it leads to a single statement: "He has succeeded who purifies it, and he has failed who instills it [with corruption]."2
The surah then illustrates the point with Thamud, who "denied [their prophet] by reason of their transgression." When "the most wretched of them was sent forth," the prophet Salih warned them: "[Do not harm] the she-camel of Allah or [prevent her from] her drink." "But they denied him and hamstrung her. So their Lord brought down upon them destruction for their sin and made it equal [upon all of them]."3
Why it matters
Ash-Shams sets the whole visible universe as witness to a truth about the inner life: every soul knows good from evil, and its fate depends on whether it is purified or corrupted. The Islamic tradition's teaching on purifying the soul (tazkiyat al-nafs) draws on these verses. To read Ash-Shams in Arabic with translations and recitation, open it on Quran.com.