He heard the Messenger of Allah ﷺ, when he raised his head from bowing in the final cycle of the dawn prayer, say after pronouncing "Allah hears whoever praises Him, our Lord, to You belongs all praise," "Allah, curse so-and-so, so-and-so, and so-and-so." Then Allah Almighty revealed "Not for you, [O Muhammad, but for Allah], is the decision whether He should [cut them down] or forgive them or punish them, for indeed, they are wrongdoers" [Aal Imran 3:128].
حدثنا علي بن إسحاق حدثنا عبد الله بن المبارك أخبرنا معمر
أنه سمع رسول الله ﷺ إذا رفع رأسه من الركوع في الركعة الآخرة من الفجر يقول اللهم العن فلانا وفلانا وفلانا بعدما يقول سمع الله لمن حمده ربنا ولك الحمد فأنزل الله تعالى {ليس لك من الأمر شيء أو يتوب عليهم أو يعذبهم فإنهم ظالمون}
Its isnad is sahih, and it is a longer version of the one before it. We noted at 5674 that Ibn Kathir, in his Tafsir 2:238, cited the narration of Mamar from Zuhri from Sahih Bukhari. So this and the one before it are Mamar's narration, and Bukhari related it in three places, through the route of Abdullah bin Mubarak from Mamar, at 7:281, 170, and 13:263–264, except that "Abdullah bin Mubarak" appears in H as "Ubaydullah bin Mubarak," which is a clear error. We have corrected it based on K and M.