Sahih al-Bukhari 6013
صحيح البخاري#6013SahihNarrated Jarir bin `Abdullah:The Prophet (ﷺ) said, "He who is not merciful to others, will not be treated mercifully
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 78:44