What is the ruling on an employee signing two contracts for a car purchased for him by the bank through murabahah, with different profit rates based on whether he continues in service or retires?

A contract in which the profit fluctuates between two percentages (10% if the employee stays, and 15% if they do not stay) is impermissible. The contract must be decisive and specific regarding a single profit, because indecisiveness and linking the matter to the future is considered "two transactions in one transaction," which is forbidden by Islamic law.