What is the ruling on agreeing with a contractor to finish a house in exchange for 10% of the costs paid by the contractor, with the amount being paid in easy monthly installments?

This transaction can be carried out through an Istisna' (manufacturing) contract for the required finishing, with a fixed total price, taking into account a known payment term. This is permissible according to the preponderant opinion. The resolution of the Islamic Fiqh Academy states that the Istisna' contract is binding on both parties if its pillars and conditions are met. It stipulates that the type, kind, quantity, and specifications of the manufactured item must be clearly stated, the deadline must be determined, and it is permissible for the entire price to be deferred or paid in installments.