Sahih Muslim 6767
صحيح مسلم#6767SahihUbayy b. Ka'b reported that Allah's Messenger (ﷺ) said:The young man whom Khadir killed was a non-believer by his very nature and had he survived he would have involved his parents in defiance and unbelief
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: 46:45