What is the ruling on selling products for cash at one price, and for installments at the same cash price, with the bank taking a 10% commission from the company without the customer's knowledge? Is this considered usury (riba)?

It is forbidden to involve the bank in the aforementioned installment sale. This involves two scenarios:

The first: The customer purchases the commodity in installments, and the merchant then transfers the transaction to the bank to receive the full amount immediately, but at a reduced price. This is forbidden usury (riba) because it involves selling a monetary debt for less than its value, and it encompasses both riba al-nasi'ah (usury of delay) and riba al-fadl (usury of surplus).

The second: The purchase is made with the buyer signing for the bank, or signing a tripartite contract that includes the buyer, the seller, and the bank, stipulating that the bank will provide the financing. This constitutes an interest-based loan (riba) between the bank and the customer.

Both scenarios are forbidden. In the first, the merchant is a usurer along with the bank, and in the second, the merchant is an assistant to usury.

The Messenger of Allah, peace and blessings be upon him, cursed the one who consumes riba, the one who feeds it, its scribe, and its two witnesses, and he said: "They are all equal," due to their assistance in falsehood.

The shop owner and anyone involved in these sales must repent to Allah Almighty. It is not permissible to participate in this forbidden sale or to assist in it.