What is the expiation for someone who bought merchandise and received it, then forgot and unintentionally took other merchandise?

The goods taken by the person belong to the shop owner, and the taker's responsibility is not discharged until they are returned, according to the hadith (definition): "On the hand is what it took until it returns it." If he consumed them, he must return their equivalent or their value if an equivalent is not available. He must repent if his action was intentional. If it was by mistake, there is no sin upon him, according according to the hadith: "Raised from my Ummah are error and forgetfulness." However, the رفع الإثم (lifting of sin) does not negate the obligation to return the right to its owners.