It is narrated from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever reaches the morning (Fajr) without having prayed witr, there is no witr for him (at that time)." This hadith is sahih (authentic) on the condition of Imam Muslim, but they did not record it, and it has a supporting narration (shahid) with an authentic chain.