Abu Dawud Book 2, Hadith Number 1337.

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

Narated By Sa’d b. Hisham : I divorced my wife. I then came to Medina to sell my land that was there so that I could buy arms and fight in battle. I met a group of the Companions of the Prophet (PBUH). They said: Six persons of us intended to do so (i.e. to divorce their wives and purchase weapons), but the Prophet (PBUH) prohibited them. He said: For you in the Apostle of Allah (PBUH) there is an excellent model. I then came to Ibn ‘Abbas and asked him about the witr observed by the Prophet (PBUH). He said: I point to you a person who is most familiar witr prayer observed by the Apostle of Allah (PBUH). Go to ‘Aisha. While going to her I asked Hakim b. Aflah to accompany me. He refused, but I adjured him. He, therefore, went along with me. We sought permission to enter upon ‘Aisha. She said: Who is this? He said: Hakim b. Aflah. She asked: Who is with you? He replied: Sa’d b. Hisham. She said: Hisham son of ‘Amir who was killed in the Battle of Uhad. I said: Yes. She said: What a good man ‘Amir was! I said: Mother of the faithful, tell me about the character of the Apostle of Allah (PBUH). She asked: Do you not recite the Qur’an? The Apostle of Allah (PBUH) was the Qur’an. I asked: Tell me about his vigil and prayer at night. She replied: Do you not recite: “O thou folded in garments” (lxxiii. 1) I said: Why not?

The narrator said: I came to Ibn ‘Abbas and narrated all this to him. By Allah, this is really a tradition. Had I been on speaking terms with her, I would not have come to hear it from her mouth. I said: If I knew that you were not on speaking terms with her, I would have never narrated it to you.