Sahih Muslim 4381
صحيح مسلم#4381SahihAbdullah b. (Mas'ud) reported Allah's Messenger (ﷺ) as saying:The first (thing) that will be decided among people on the Day of Judgment will pertain to bloodshed
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: 28:40