Prayer at Night (Tahajjud)

Bukhari :: Book 2 :: Volume 21 :: Hadith 238

Narrated 'Abdullah bin 'Umar :

A man said, "O Allah's Apostle! How is the prayer of the night?" He said, "Two Rakat followed by two Rakat and so on, and when you apprehend the approaching dawn, offer one Raka as Witr."