First: The default principle is that a person is held accountable for their actions, not the actions of others. If the seller makes an error, it is the seller’s responsibility unless it is a right related to the seller known to the buyer, and the buyer deliberately conceals it; in that case, the buyer is accountable for the concealment.

Second: There are different types of seller errors:

• One type is an agreement on the price followed by a mistake in the calculation resulting in underpayment. The buyer must return the excess amount as it becomes like a debt in exchange for the product.
• Another type is an agreement on the price with a discount given. In this case, the seller’s statement is accepted, and the buyer is not required to inquire further.

Third: In the example provided in the question, it is necessary to further inquire about the seller’s intention because no sale was completed. It is not permissible to take someone else’s money without a contract of exchange (such as a sale), a contract of donation (such as a gift), or a contract of usufruct (such as a loan for use).

Therefore, if a person receives an item after canceling the purchase, they must return to the seller to determine whether it was sent as an exchange for a price or as a gift.

Fatwa issued by Dr. Khālid Naṣr