Sahih Muslim 699
صحيح مسلم#699SahihA'isha reported:Whenever the Messenger of Allah (ﷺ) intended to sleep after having sexual intercourse, he performed ablution as for the prayer before going to sleep
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: 3:21