Az-Zalzalah, "The Earthquake," is the ninety-ninth surah — 8 verses.1 It is classed as Medinan in the standard Mushaf, though many scholars hold it to be Meccan.
What it is about
The surah describes the end of the world as a final earthquake: "When the earth is shaken with its [final] earthquake and the earth discharges its burdens and man says, 'What is [wrong] with it?' — that Day, it will report its news because your Lord has inspired [i.e., commanded] it." The ground people walked on becomes a witness, and "that Day, the people will depart separated [into categories] to be shown [the result of] their deeds."2
It ends with two short verses: "So whoever does an atom's weight of good will see it, and whoever does an atom's weight of evil will see it."3 When the Prophet ﷺ was asked about a matter on which nothing specific had been revealed, he pointed to these verses as "this comprehensive Verse which includes everything."4
Why it matters
Az-Zalzalah's closing verses state the principle of moral accountability in its fullest form: no good deed is too small to count and no wrong too small to be answered for. They teach that nothing a person does is wasted or forgotten. To read Az-Zalzalah in Arabic with translations and recitation, open it on Quran.com.