Nafi' said,“I was with Ibn ‘Umar in Mecca when the sky was cloudy and he was afraid the morning might have come, so he observed a witr with one rak'a. The sky then cleared and he saw that it was still night, so he made it a pair by praying one rak'a; then he prayed series of two rak'as, and when he was afraid morning was near he observed a witr with one.”Malik transmitted it.