It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "The night prayer is two by two rak'ahs. So when one of you fears the arrival of dawn, let him pray one rak'ah, which will make his (preceding) prayer odd (witr)."
No one narrated this hadith from Za'idah (may Allah have mercy on him) except Husayn (may Allah have mercy on him).