`Umar bin Al-Khattab gave a horse in charity in Allah's Cause and later he saw it being sold in themarket and intended to purchase it. Then he went to the Prophet (ﷺ) and asked his permission. TheProphet said, "Do not take back what you have given in charity." For this reason, Ibn `Umar neverpurchased the things which he had given in charity, and in case he had purchased something(unknowingly) he would give it in charity again.