It is narrated from Sayyidah Aishah (may Allah be pleased with her) that she said: "The Messenger of Allah (peace and blessings be upon him) used to offer thirteen rak'ahs of prayer in the time between Isha (and Fajr), of which he would pray five rak'ahs as witr, giving the salam only at the fifth rak'ah."
Hadith Referenceمسند أبي يعلى الموصلي / مسند عائشة / 4526