Muwatta Malik Book 7, Hadith 21
Yahya related to me from Malik from Ibn Shihab that Sad ibn Abi
Waqqas used to pray witr after isha with one raka.
Malik
said, "This is not the situation with us. Rather three is the minimum
for witr."
Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to say the taslim between the two rakas and the one raka of witr so that he could order something he needed.
Yahya related to me from Malik from Abdullah ibn Dinar that Abdullah ibn Umar used to say, "The maghrib prayer is the witr of the daytime prayers."
Malik said, "If someone prays witr at the beginning of the night, and goes to sleep, and then wakes up and it seems good to him to pray, let him pray, two rakas at a time. That is what I like most of what I have heard."