(59) باب هَلْ يَشْتَرِي صَدَقَتَهُ
Narrated `Abdullah bin `Umar:
`Umar bin Al-Khattab gave a horse in charity in Allah's Cause and later he saw it being sold in the market and intended to purchase it. Then he went to the Prophet (ﷺ) and asked his permission. The Prophet said, "Do not take back what you have given in charity." For this reason, Ibn `Umar never purchased the things which he had given in charity, and in case he had purchased something (unknowingly) he would give it in charity again.
Reference: Sahih al-Bukhari 1489
In-book reference: Book 24, Hadith 90
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 24, Hadith 566