The ruling on a man renting out his car for a fixed amount each day

Question:
He says: Honorable Shaykh, may Allah grant you success, is it permissible for me to enter into a profit-sharing partnership (mudarabah) in limousine cars, where he operates them and pays me two hundred riyals every day?

Answer:
No, fixing a specific amount is not permissible. However, you may give him the car and say, "Rent it out and operate it, and whatever is earned will be divided between us by quarters, halves, or thirds, whether little or much." But if you impose a specific amount on him, that is not permissible.