Purchasing on installment through a bank or otherwise.

Question:
I want to buy a house, so I went to one of the banks, and they said: "We will buy this house for you and sell it to you on installment." What is the Islamic ruling on this?

Answer:
Answer: If the bank or any other entity buys the house and owns it fully, then wants to sell it to you or to someone else, there is nothing wrong with that. But if an agreement and mutual understanding are reached between you and them before they buy the house, and the contract is concluded between you and them, and then they go to buy the house after the contract between you and them, this is not permissible. This is because the bank sold something it does not own before owning it. If the bank has houses, cars, or goods that it owns and has in its possession, it is permissible for it to sell to whoever buys from it. However, if the goods are not in its possession, and only after they conclude the contract do they go to the bank or another entity to buy the item that was agreed upon, such as the house, this is not permissible because it sold what it does not own.