Sahih Muslim | Book 7 | Hadith Number 2821

Narrated by Ghunaim b. Qais
Ghunaim 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.