Sahih Muslim 2969
صحيح مسلم#2969SahihGhunaim b. Qais said:I asked Sa'd b. Abu Waqqas (Allah be pleased with him) about Mut'a, whereupon he said: We did that, and it was the day when he was an unbeliever living in (one of the) houses of Mecca
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: 15:178