Bismillah Walhamdulillah Was Salaatu Was Salaam ‘ala Rasulillah

Narrated ‘Abdullah bin ‘Umar (Radi-Allahu ‘anhu):

A man said, “O Allah’s Apostle! (Sallallahu ‘Alaihi Wa Sallam) 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.”

Bukhari Vol. 2 : No. 238