Sahih Muslim 3751
صحيح مسلم#3751SahihSa'id b. Jubair reported that Mus'ab b. Zubair did not effect 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 (ﷺ) effected separation between the two members of Banu al-'Ajlan
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: 19:9