Abu Dawud Book 2, Hadith Number 1362.

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

Narated By ‘Abd Allah b. Abbas : I spent a night with Maimunah, wife of the Prophet (PBUH), who was also my(Ibn’ Abbas’s) maternal aunt. I lay towards the width of the pillow and the Apostle of Allah (PBUH) and his wife slept towards its length. The Apostle of Allah (PBUH) slept. When half the night passed, or a little before it or a little after it, the Apostle of Allah (PBUH) awoke and began to rub his face (eyes) to remove the sleep. He then recited ten verses from the last part of Surah ‘Al-Imran. He then came to a bag of water that was hanging. He performed ablution from it and performed his ablution well. He then stood up and prayed. I also got up and did as he did. I then went and stood at his side. The Apostle of Allah (PBUH) placed his right hand upon my head and took me by my ear twisting it. He then prayed two rak’ahs, then two rak’ahs, then two rak’ahs, the two rak’ahs, then two rak’ahs, then two rak’ahs. The narrator al-Qa’nabi said: Six times. He observed the witr prayer, and then slept until the mu’adhdhdin came. He got up and prayed two light rak’ahs; and then he came out and offered the dawn prayer.