Sahih Bukhari
Witr Prayer
Volume: 002 / Book Number: 016 / Hadith Number: 108
Narrated 'Aisha:
Allah's Apostle used to pray eleven Rakat at night and that was his night prayer and each of his prostrations lasted for a period enough for one of you to recite fifty verses before Allah's Apostle raised his head. He also used to pray two Rakat (Sunna) before the (compulsory) Fajr prayer and then lie down on his right side till the Muadh-dhin came to him for the prayer.