The selling price of an asset sold based on Istisna'a is agreed or determined on the contractual date and such a contract is binding. The price cannot be increased or decreased on account of an increase or decrease in commodity prices or labour cost. The price can be changed subject to the mutual consent of the contracting parties due to alteration or modifications to the contract or unforeseen contingencies, which is a matter for the commercial decision of the bank and can result in a lower profit margin.