Is paying a security deposit before concluding a Murabaha contract permissible in Sharia and not considered usury?

It is permissible to take what is called a "seriousness margin" (hamish al-jiddiyah) in murabahah (cost-plus financing) to verify the client's financial capability and to compensate the institution for damages in the event of their reneging on their binding promise.

This seriousness margin is not an earnest payment (urbun); it is either a trust for safekeeping, which may not be disposed of, or an investment trust with the client's permission.

If the client reneges, the institution has the right to deduct only the amount of actual damage (the difference between the cost of the commodity and its selling price to someone other than the ordering party). The compensation does not include what is referred to as "lost opportunity."

If the client fulfills their promise, the institution must return the seriousness margin to them. It is permissible to agree to deduct it from the price of the commodity upon the conclusion of the contract.