What is the ruling on disposing of bank interest accrued from an amount deposited in the Housing and Development Bank for reservation in a land lottery, and is it considered permissible, or must it be spent on charitable causes?

It is permissible to purchase land in installments from a bank if the bank is an agent for the state in the sale or if it genuinely bought the land and then sold it. However, if the bank's role is to finance the purchase, paying the state the price in cash and then collecting it from the client with an increase in installments, this is usury (riba) and forbidden. If the bank returns the down payment with usurious interest, then one must dispose of this interest by spending it on charitable causes.