What is the Islamic legal principle behind the statement: "If an item intervenes, there is no usury (riba); because the intervention of an item removes the transaction from the scope of prohibited usurious loans to permissible murabaha," in the case where a customer purchases goods from a supplier through a bank that pays cash and sells them to the customer on a periodic deferred payment basis under a current debit account system, with a prior agreement on the deferred purchase price in exchange for the bank paying the price of the item in cash to the supplier?

If the bank buys a commodity and takes possession of it, then sells it to the client at a profit, there is no harm in that, whether the client uses the commodity or sells it and benefits from its price. However, if the bank pays the price on behalf of the client to the seller and then collects the amount from the client with an increase, this is an interest-based loan, because no commodity intermediated the transaction. The criterion for the permissibility of the transaction is that it must be a genuine sale and purchase between the bank and the client, or a benevolent loan with no increase, in accordance with the Almighty's saying: "Allah has permitted trade and forbidden usury." Any prior contractual link between the client and the original seller must be canceled, and the contract concluded between the client and the original source must not be transferred to the bank, so that the transaction does not turn into an interest-based loan.