Sunan Abi Dawud, Book 4, Hadith 1257 (USC-MSA) ⓘ

Narrated 'Aishah: When the Messenger of Allah finished his prayer late in the night, he would see. If I was awake, he would talk to me. If I was sleeping, he would awaken me, and pray two rak'ahs, then he would lie down as long as the mu'adhdhin came to him and call him for the dawn prayer. Then he would pray two rak'ahs lightly and come out for prayer.

حَدَّثَنَا يَحْيَى بْنُ حَكِيمٍ، حَدَّثَنَا بِشْرُ بْنُ عُمَرَ، حَدَّثَنَا مَالِكُ بْنُ أَنَسٍ، عَنْ سَالِمٍ أَبِي النَّضْرِ، عَنْ أَبِي سَلَمَةَ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ عَائِشَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا قَضَى صَلاَتَهُ مِنْ آخِرِ اللَّيْلِ نَظَرَ فَإِنْ كُنْتُ مُسْتَيْقِظَةً حَدَّثَنِي وَإِنْ كُنْتُ نَائِمَةً أَيْقَظَنِي وَصَلَّى الرَّكْعَتَيْنِ ثُمَّ اضْطَجَعَ حَتَّى يَأْتِيَهُ الْمُؤَذِّنُ فَيُؤْذِنَهُ بِصَلاَةِ الصُّبْحِ فَيُصَلِّي رَكْعَتَيْنِ خَفِيفَتَيْنِ ثُمَّ يَخْرُجُ إِلَى الصَّلاَةِ ‏.‏