Az-Zalzala ('The Earthquake'), 8 verses often placed in Medina, describes the earth's final convulsion when it will 'report its news' and people come forth in scattered groups to see their deeds. Its closing measure is famous: 'whoever does an atom's weight of good will see it, and whoever does an atom's weight of evil will see it' (99:7-8).
Az-Zalzala, though generally listed as Medinan in the standard order, was read as Meccan by early authorities including Ibn Mas'ud, Ata and Mujahid, a genuine point of classical disagreement rather than a settled fact. Its closing measure, that whoever does even an atom's weight of good or evil will see it (99:7-8), became one of the most widely quoted individual verses in Islamic popular ethics precisely because of its deliberate scale, using the smallest conceivable unit, dharra, to insist that no act, however minor, escapes account, a rhetorical strategy distinct from the surah's otherwise apocalyptic register of a convulsing, testifying earth. Classical commentators read the surah's image of the earth 'reporting its news' because its Lord has inspired it to do so (99:4-5) as attributing testimony to the created world itself rather than only to human or angelic witnesses, an idea scholars of Quranic theology connect to a wider pattern across the text in which inanimate creation is repeatedly described as capable of praise, obedience and, here, direct testimony. The surah's closing measure of an atom's weight of good or evil is frequently paired in later homiletic use with Al-Adiyat, the short surah immediately following it, itself closing on a related theme of what is hidden in the breast being laid bare.