Finance says money is interchangeable and mental accounting is a BIAS. This means the amount you budget to be expensed out on furniture can be used to buy groceries. There should be a clear and crisp understanding of religious rules in terms of lending and borrowing and the general conventional banking rules. The fundamentals, policies, and parameters of Islamic Banking are different from that of conventional Banking. Yes, there is a factor of interest that consists of Kibor and spread, yet the execution of the transaction is what matters. Giving an example, why do you ask the butcher to recite Bismillah before slaughter, because that assures that this execution has completed the requirements to make it halal.