Sahih Muslim
The Book of Prayers (Kitab Al-Salat)
Book Number: 004 / Hadith Number: 1720
'A'isha reported that the Apostle of Allah (may peace be upon him) heard a person reciting the Qur'an at night. Upon this he said: May Allah show mercy to him; he has reminded me of such and such a verse which I had missed in such and such a surah.