Sahih Muslim Book 9, Hadith Number 3560.

Chapter: Li’an (Invoking curse).

Sa’id b. Jubair reported that Mus’ab b. Zubair did not affect separation between the Mutala’inain (invokers of curses). Sa’id said: It was mentioned to ‘Abdullah b. Umar (Allah be pleased with them) and he said: Allah’s Apostle (may peace be upon him) effected separation between the two members of Banu al-‘Ajlan.