Sahih Muslim Book 9, Hadith Number 3555.

Chapter: Li’an (Invoking curse).

Ibn Shihab narrated about the invokers of curses and the practice of (li’an) based on the authority of Sahl b. Sa’d, of the tribe of Sa’ida, that a person from the Ansar came to Allah’s Apostle (may peace be upon him) and said: Allah’s Messenger, tell me about the person who found a man with his wife. The remaining part of the hadith is the same (but) with this addition: They invoked curses in the mosque and I was present there. And he narrated in the hadith: He divorced her with three pronouncements before Allah’s Messenger (may peace be upon him) commanded him (to get separation). He separated from her in the presence of Allah’s Apostle (may peace be upon him), whereupon he said: There is a separation between the invokers of curses.