It is narrated from Sayyiduna Abu Qatadah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) asked Sayyiduna Abu Bakr (may Allah be pleased with him): "When do you pray witr?" He replied: I pray witr before I sleep. And he (peace and blessings be upon him) asked Sayyiduna Umar (may Allah be pleased with him): "When do you pray witr?" He replied: I sleep, then (after waking) I pray witr. So he (peace and blessings be upon him) said to Sayyiduna Abu Bakr (may Allah be pleased with him): "You have taken the path of caution - or of certainty -", and he said to Sayyiduna Umar (may Allah be pleased with him): "You have taken the path of strength (resolve)." This hadith is sahih (authentic) on the condition of Imam Muslim, but they did not record it, and it has a supporting narration (shahid) with an authentic chain.