Sunan Ibn Majah — Establishing the Prayer and the Sunnah Regarding Them — Hadith No: 1185
Translation
It was narrated that Masruq said:“I asked ‘Aishah about the Witr of the Messenger of Allah (ﷺ). She said: ‘He prayed Witr at every part of the night, at the beginning, in the middle and at the end, when he died (he would perform it) just before dawn.’”