Sahih Muslim Book - 6, Hadith - 1718

وَحَدَّثَنِى حَرْمَلَةُ بْنُ يَحْيَى حَدَّثَنَا ابْنُ وَهْبٍ أَخْبَرَنِى عَمْرُو بْنُ الْحَارِثِ عَنِ ابْنِ شِهَابٍ عَنْ عُرْوَةَ بْنِ الزُّبَيْرِ عَنْ عَائِشَةَ زَوْجِ النَّبِىِّ -صلى الله عليه وسلم- قَالَتْ كَانَ رَسُولُ اللَّهِ -صلى الله عليه وسلم- يُصَلِّى فِيمَا بَيْنَ أَنْ يَفْرُغَ مِنْ صَلاَةِ الْعِشَاءِ - وَهِىَ الَّتِى يَدْعُو النَّاسُ الْعَتَمَةَ - إِلَى الْفَجْرِ إِحْدَى عَشْرَةَ رَكْعَةً يُسَلِّمُ بَيْنَ كُلِّ رَكْعَتَيْنِ وَيُوتِرُ بِوَاحِدَةٍ فَإِذَا سَكَتَ الْمُؤَذِّنُ مِنْ صَلاَةِ الْفَجْرِ وَتَبَيَّنَ لَهُ الْفَجْرُ وَجَاءَهُ الْمُؤَذِّنُ قَامَ فَرَكَعَ رَكْعَتَيْنِ خَفِيفَتَيْنِ ثُمَّ اضْطَجَعَ عَلَى شِقِّهِ الأَيْمَنِ حَتَّى يَأْتِيَهُ الْمُؤَذِّنُ لِلإِقَامَةِ.

It was narrated that 'Aishah, the wife of the Prophet (s.a.w), said: "Between finishing the 'Isha' prayer - which the people call Al-'Atamah - and dawn, the Messenger of Allah (s.a.w) would pray eleven Rak'ah, saying the Taslim between every two Rak'ah, and making them an odd number with one Rak'ah. When the Mu'adhdhin fell silent following the call to Fajr prayer, and he could see the dawn, and the Mu'adhdhin came to him, he would pray two brief Rak'ah, then lie down on his right side, until the Mu'adhdhin came to him for the Iqamah."