Sahih al-Bukhari 2970
صحيح البخاري#2970SahihNarrated `Umar bin Al-Khattab:I gave a horse to be used in Allah's Cause, but later on I saw it being sold. I asked the Prophet (ﷺ) whether I could buy it. He said, "Don't buy it and don't take back your gift of charity
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: 56:179