Urwah narrates from Sayyidah Aishah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) used to pray eleven rak'ahs between Isha and the break of dawn, saying the salam after every two rak'ahs and praying one rak'ah of witr. He (peace and blessings be upon him) would prostrate for as long as it takes one of you to recite fifty verses. When the mu'adhdhin fell silent after the Fajr adhan, he (peace and blessings be upon him) would pray two light rak'ahs, then lie down on his right side until the mu'adhdhin came to inform him (peace and blessings be upon him) of the prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4679