Al-Qasim bin Muhammad narrates from Sayyidah Aishah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) used to pray thirteen rak'ahs of night prayer, and these included the witr and the two rak'ahs of Fajr.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4675