Sahih al-Bukhari 5038
Sahih al-Bukhari · Book 66: Virtues of the Qur'an · Forgetting the Qur'an. And can one say: “I forgot such and such a Verse?
Narrated Aisha:
حَدَّثَنَا أَحْمَدُ بْنُ أَبِي رَجَاءٍ ، حَدَّثَنَا أَبُو أُسَامَةَ ، عَنْ هِشَامِ بْنِ عُرْوَةَ ، عَنْ أَبِيهِ ، عَنْ عَائِشَةَ ، قَالَتْ سَمِعَ رَسُولُ اللَّهِ صلى الله عليه وسلم رَجُلاً يَقْرَأُ فِي سُورَةٍ بِاللَّيْلِ فَقَالَ " يَرْحَمُهُ اللَّهُ لَقَدْ أَذْكَرَنِي كَذَا وَكَذَا آيَةً كُنْتُ أُنْسِيتُهَا مِنْ سُورَةِ كَذَا وَكَذَا " .
Allah's Messenger (ﷺ) heard a man reciting the Qur'an at night, and said, "May Allah bestow His Mercy on him, as he has reminded me of such-and-such Verses of such-and-such Suras, which I was caused to forget."