Sahih Muslim 1737
صحيح مسلم#1737SahihMasruq reported on the authority of 'A'isha that she said that the Messenger Of Allah (ﷺ) used to observe the Witr prayer every night, maybe in the early part of night, at midnight and in the latter part, finishing his Witr at dawn
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 6:166