Sahih Muslim 6465
صحيح مسلم#6465SahihJubair b. Mut'im reported Allah's Messenger (ﷺ) as saying:There is no alliance (hilf) in Islam but (the hilf) established in the pre-Islamic days (for good). Islam intensifies and strengthens it
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: 44:294