The Sale of Al-'Eenah is forbidden
Question :
If I bought a car for someone for installment payments (knowing that with the installment payments the price of the car is more), then he requested for me to buy it from him for less than what he bought it for from me, what is the ruling on that?
Answer:
This issue is called the issue of Al-'Eenah and its ruling is that it is forbidden. The basis of this is what is reported from the Islamic evidences that prove this is prohibited.
And success comes from Allâh. May Allah send blessings and peace upon our Prophet Muhammad, his family and his Companions.
Source:
The Permanent Committee
Fatawa Islamiyah, Vol. 4 Page 442