Abu Dawud Book 2, Hadith Number 1335.

Chapter : On the number of rakahs of the prayer at night.

Narated By ‘Aisha : The Prophet of Allah (PBUH) used to pray thirteen rak’ahs during the night. He would offer eight rak’ahs observing the witr with one rak’ah. Then he prayed (the narrator Muslim said) two rak’ahs after witr prayer in sitting position. When he wished to bow, he stood up and bowed. He used to pray two rak’ahs between the call to the dawn prayer and the iqamah.