What is the correct action to take after the buyer has relinquished the car and the money, refused to complete the payment, and is it permissible to sell the car, collect the remainder of the price, and return the surplus to the buyer, knowing that its condition has deteriorated, and does his relinquishment necessitate returning his money, and how can the money be returned to him if he is difficult to contact?

"A sale is a binding contract for both parties. Therefore, the buyer must pay the remaining price of the car. The seller is not obligated to cancel the sale, although it is recommended. If the buyer relinquishes the car in exchange for the remaining price, it is as if he is selling it to the seller for a lower price. This falls under the forbidden 'inah sale, unless the condition of the item has changed and deteriorated, in which case it is permissible to purchase it for less than its original price; because the reduction in price here is due to the defect in the sold item, not a means to engage in usury. In this case, the questioner is not obliged to sell it and return the surplus beyond his right to its owner, but if he does so, he has done well."