Sahih Muslim 1720
صحيح مسلم#1720SahihA'isha reported:The Messenger of Allah (ﷺ) used to observe thirteen rak'ahs of the night prayer. Five out of them consisted of Witr, and he did not sit, but at the end (for salutation)
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: 6:149