Is it permissible to buy a device from the financially distressed debtor at market price and retrieve the remaining amount of the debt, or to sell the device to another party to obtain the remaining amount, while returning the difference to the debtor?

If the buyer defaults on paying the installments for a device sold on credit, the seller is permitted to take it from him, sell it on his behalf, recover his due, and return the remainder to the buyer. This falls under the concept of agency (wakalah). However, for the seller to buy the device from the buyer at a lower price is considered "bay' al-inah" (a sale of buy-back), which is forbidden, unless the device's price has decreased due to use. The Prophet, peace and blessings be upon him, forbade bay' al-inah. It is permissible to purchase the device from the buyer at the original price or more, but it is forbidden at a lower price, except in cases such as the commodity's value decreasing due to change, or receiving the deferred payment for it and then purchasing it as a separate transaction, or purchasing it from someone other than the original buyer (such as his heir).