Sahih Muslim 1736
صحيح مسلم#1736SahihA'isha reported:The Messenger of Allah (ﷺ) observed the Witr prayer every night and he completed Witr at the time of 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: 6:165