Sayyida Aisha (may Allah be pleased with her) said: The Messenger of Allah (peace and blessings be upon him) performed Witr in every part of the night, and towards the end, his Witr would be close to the morning.
Hadith Referenceسنن دارمي / من كتاب الصللاة / 1626
In other narrations, it is mentioned that the Prophet sallallahu alayhi wa sallam performed the witr prayer at the beginning of the night, in the middle, and at the end of the night as well. From the aforementioned narration, it is understood that the time for witr is from after the ‘Isha prayer until the break of dawn (fajr). The Messenger of Mercy, Muhammad sallallahu alayhi wa sallam, for the ease of the ummah, declared it permissible to perform witr at any time during the night after ‘Isha, whenever possible.