What is the ruling on placing a deposit in an Islamic bank and purchasing a car from it through an Islamic Murabaha system for an amount exceeding the original price with a 12% profit, guaranteed by this deposit, such that the installments are paid from the deposit's profit? And what is the ruling on submitting documents for a plot of land instead of the car to expedite obtaining the amount? And what is the correct Murabaha system, and what should I do about the installments I have already paid?

Murabaha to a purchasing orderer is permissible with conditions and regulations. There is no difference between purchasing land or real estate. It is permissible for the price of the commodity in installments to be greater than its cash price. There is no objection to the deposit serving as collateral for the sale, as a type of pledge. As for paying installments from the interest of the deposit, if it is profit resulting from Mudarabah (definition), then there is no problem. But if it is specified usurious interest, then it is forbidden, and one must dispose of it by spending it on general Muslim welfare.