موطا امام مالك رواية ابن القاسم
Muwatta Imam Malik (Riwayat Ibn al-Qasim)
Discussion on Voluntary and Sunnah Prayers
Description of Witr prayer
Hadith 167
35- وبه: أن رسول الله صلى الله عليه وسلم كان يصلي بالليل إحدى عشرة ركعة يوتر منها بواحدة. فإذا فرغ منها اضطجع على شقه الأيمن.
And with the same chain (it is narrated from Sayyidah Aisha, may Allah be pleased with her) that the Messenger of Allah, peace and blessings be upon him, used to pray eleven rak'ahs at night. Among them, he would perform one witr (at the end). When he finished this, he would lie down on his right side.
