مُوَطَّأُ مَالِكٍ
Muwatta Malik 284
Tahajjud
وَحَدَّثَنِي مَالِكٌ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّ عَائِشَةَ، زَوْجَ النَّبِيِّ صلى الله عليه وسلم قَالَتْ إِنْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم لَيُخَفِّفُ رَكْعَتَىِ الْفَجْرِ حَتَّى إِنِّي لأَقُولُ أَقَرَأَ بِأُمِّ الْقُرْآنِ أَمْ لاَ
Malik related to me from Yahya ibn Said that A'isha, the wife of the Prophet, (ﷺ), said, "The Messenger of Allah, (ﷺ), used to pray the two rakas of the dawn (fajr) so quickly that I would say to myself 'Has he recited the umm al-Qur'an or not?' "
Arabic/English book reference: Book 7, Hadith 30