What is the ruling on the transaction called "Al-Tayseer Al-Ahli" (The National Facilitation) from the National Bank, in which the bank buys goods and sells them to the customer at a deferred price, with the possibility for the customer to authorize the bank to sell his goods, and what must be done by someone who has engaged in this transaction if it is impermissible?

It is not permissible to deal with banks using murabaha or tawarruq if the Sharia conditions are not met. These conditions are: that the bank owns the commodity before selling it, that it takes possession of it before selling it to the customer, and that the buyer sells it to someone other than the seller. As for organized banking tawarruq practiced by some banks, it is forbidden because it is a ruse for interest-based lending, and the "storage certificate" does not represent real possession of the commodity. The Salaf forbade selling a commodity on credit and then authorizing the seller to sell it.