Malik said he heard that a man asked Ibn ‘Umar whether the witr was obligatory, and ‘Abdallah said, “God’s Messenger observed the witr and the Muslims observed the witr.” The man kept repeating his question and ‘Abdallah kept saying, “God’s Messenger observed the witr and the Muslims observed the witr.”
Abu Sa'id reported God’s Messenger as saying, “If anyone over-sleeps and misses the witr, or forgets it, he should pray when he remembers and when he awakes.”
‘Ali said that God’s Messenger used to pray three rak'as when observing the witr, reciting nine suras from al-Mufassal in the course of them, three in each rak'a, the last of them being “Say, He is God, One” (Al-Qur’an; 112).
Buraida said he heard God’s Messenger say, “The witr is a duty, so he who does not observe it does not belong to us; the witr is a duty, so he who does not observe it does not belong to us; the witr is a duty, so he who does not observe it does not belong to us.”
