What is the ruling on two partners buying a house, where one pays a quarter and the other pays three quarters, and the one who paid a quarter lives in it while paying rent to the one who paid three quarters, with the rent decreasing annually until he fully owns the house?

This transaction is permissible if there is a partnership in purchasing the house without obligating the questioner to anything, then a separate lease contract is drawn up in which the questioner pays rent for his partner's share. Then, if he acquires funds, he buys his partner's share to the extent of what he has, with the rent for the remainder being adjusted by agreement. This transaction is not a lease ending in ownership; the rent is genuine, and ownership occurs through an annual purchase and a separate amount.