What is the ruling on purchasing a house from a real estate company if part of its price is paid through usurious banks affiliated with the state, knowing that the state provides a non-refundable portion of the price as a subsidy?

The aforementioned transaction is not permissible in Islamic law because it involves a loan with interest, which is usury (riba) and is unanimously forbidden, whether the lender is a bank, a state, or otherwise. It is not permissible to purchase a house in this manner except in a case of dire necessity, which means that the person cannot find any dwelling, even for rent.