From Sahih Muslim (Hadith 3611):
This hadith has been reported on the authority of AbuSa'id (al-Khudri) (Allah be pleased with him) through another chain of transmitters and the words are:They took captives (women) on the day of Autas who had their husbands. They were afraid (to have sexual intercourse with them) when this verse was revealed:" And women already married except those whom you right hands posses" (iv)
Reference: Muslim 3611