Is it permissible to purchase a car in installments from Faysal Islamic Bank, guaranteed by a deposit that yields profit for both the bank and the owner of the deposit, knowing that the profit is not fixed?

If the questioner intends to purchase the car through a Murabaha (cost-plus financing) system, it is a condition for the transaction's permissibility that the bank adheres to Sharia rulings. As for opening an investment deposit with an Islamic bank and pledging it to the bank until the Murabaha installments are fulfilled, there is no objection to it. The resolution of the Islamic Fiqh Academy stipulated the permissibility of pledging deposits (whether demand or investment deposits), provided that a procedure is implemented to prevent the account holder from disposing of it throughout the duration of the pledge. If the bank is the mortgagee, the funds must be transferred to an investment account so that the guarantee is negated and it transforms from a loan to a Mudaraba (profit-sharing) partnership, and the account holder is entitled to their profits.