Abu Salamah asked Sayyidah Aishah (may Allah be pleased with her) about the night prayer of the Messenger of Allah (peace and blessings be upon him), and she said: He (peace and blessings be upon him) used to pray thirteen rak'ahs. He (peace and blessings be upon him) prayed nine rak'ahs standing, among which was the witr, and two rak'ahs sitting. When he (peace and blessings be upon him) intended to prostrate, he would stand up, then bow and prostrate. He did this after the witr, and he would pray two rak'ahs when he heard the call to prayer (adhan) for the morning.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4818