Is the bank's sale of a specific apartment to a customer in monthly installments over 25 years, with the bank's purchase price for the apartment set at $20,000 and the monthly installment due at $170, considered a usurious transaction or not?

If the bank purchases an apartment for a customer and then sells it to him for a deferred price with an increase, this is a Murabaha sale that is permissible in Islamic law. An increase in the deferred price over the current price is also permissible. If the sale is valid, there is no objection to dealing with an interest-based bank that conducts such permissible sales. It is permissible for the bank to stipulate a mortgage on the house until it receives its price, but it is not permissible for it to stipulate that ownership not be transferred to the buyer.