Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: A man came and asked the Prophet (peace and blessings be upon him) about witr, and I was between them. He (peace and blessings be upon him) said: "The night prayer is two rak'ahs at a time. When it is the last part of the night, pray one rak'ah of witr, then pray two rak'ahs before Fajr", meaning two rak'ahs before the Fajr prayer.
(b) Asim al-Ahwal and Lahiq bin Humayd narrate a similar hadith, with some additional words, that he (peace and blessings be upon him) said: "Hasten to pray one rak'ah before the morning."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4771