Sa’d bin Hisham reports: Sayyida Aisha (may Allah be pleased with her) was asked about the Witr prayer of the Prophet (peace and blessings be upon him), so she said: We used to prepare the miswak and the water for ablution of the Prophet (peace and blessings be upon him). When Allah willed, he would get up during the night. He would use the miswak, perform ablution, then offer seven rak’ahs. He would only sit after the sixth rak’ah among them. He would sit and remember Allah Almighty and supplicate.
Hadith Referenceصحیح ابن حبان / كتاب الصلاة / 2441
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «الإرواء» (2/ 33)، «صحيح أبي داود» (1213): م مطولا، والآتي بعده بعض منه.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرطهما