—“When the Qur’an is recited, listen to it attentively and keep silent” (Q 7:204). The Messenger of Allah, peace and blessings be upon him, likewise said, “Why should I dispute with the Qur’an?” and regarding the imam he said, “When he recites, keep silent.”
Anything beyond the recitation of Fātiḥat al-Kitāb is a recommended sunnah. In the last two rakʿahs of the four-rakʿah prayers one recites only al-Fātiḥah, and the same is true of the third rakʿah of Maghrib. In all the other rakʿahs one recites al-Fātiḥah together with another surah, and there is no binding obligation beyond that.
If the imam forgets to recite Umm al-Qurʾān in his prayer, neither his prayer nor the prayer of those behind him is valid—even if they themselves have recited it—for he is like a man who omits the opening takbīr while those following him pronounce it. The report attributed to ʿUmar on this point is not authentic; what is sound is that he repeated the prayer in which he had failed to recite, and we have documented this through several chains in its proper place in al-Tamhīd.
Whoever recites only Umm al-Qurʾān in a single rakʿah, whether that rakʿah is the first or the last, has completed it without defect or shortcoming. The sunnah, however, is to add a surah alongside it in the first two rakʿahs of every prayer and in both rakʿahs of the dawn prayer; whichever surah he chooses is acceptable.
As for the scholars’ preferences concerning what to recite in the prayers, none of it is binding, because the Messenger of Allah, peace and blessings be upon him—