It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that once a man came to the service of the Prophet (peace and blessings be upon him) and inquired about the night prayer. The Prophet (peace and blessings be upon him) said: "The night prayer consists of two rak'ahs at a time, and when you fear that morning is near, then add one rak'ah to these two, and that will suffice as witr for all that you have prayed during the night."