Yahya related to me from Malik that Nafi said, "I was withAbdullah ibn Umar in Makka. The sky was clouded over and Abdullahfeared that dawn was approaching so he prayed one raka for witr. Thenthe clouds cleared and he saw that it was still night, so he made hisprayers even with one raka. Then he continued to pray two rakas at atime, until when he feared the approach of dawn, he prayed one rakafor witr."
App reference: Book 7, Hadith 19
USC-MSA web (English) reference: Book 7, Hadith 19
Arabic reference: Book 7, Hadith 273