What is the ruling on one who bought his own charity in ignorance, and it became clear after the purchase that it was his charity?

The questioner : Shaykh, may Allah reward you, regarding charity: did he give it and then return to it, or was it through ignorance? And if a person sends someone to buy something for him, and he buys his own charity.

The Shaykh : If he knows, the sale is invalid.

The questioner : After he brought it to you.

The Shaykh : Yes.

The questioner : He sent someone to buy it without knowing. The one who gave it, meaning this sale, is actually the first one.

The Shaykh : Give an example.

The questioner : That is, a person gave a car to another, then found him offering it in the market, and appointed another person to buy it, telling him not to inform the giver that he is the buyer. Is this permissible?

The Shaykh : It is not permissible. That is, whether he bought it directly or through agency.

The questioner : The operative cause, O Shaykh.

The Shaykh : The operative cause is that the agent stands in the place of the one who appointed him, so he is his representative.