What are the prohibited banking transactions and the permissible ones, especially what is called "financing" under the category of loans? And what is the ruling on dealing with banks through installments, particularly in purchasing cars?

Many banking transactions are prohibited, including: lending and borrowing with interest, time deposits, opening letters of credit, and issuing credit cards with interest.

Permissible transactions in Islamic banks include: Murabaha for the one who orders the purchase, Ijarah (leasing) and Musharakah Mutanaqisah (diminishing partnership) ending in ownership, with their stipulated conditions, joint Mudarabah (profit-sharing partnership), and the contracts of Salam (forward buying) and Istisna’ (manufacturing contract).

It is permissible to sell a car or real estate in installments with an increase in price, provided that the two parties to the contract definitively agree on the price whether paid in cash or deferred. It is not permissible for the contract to stipulate installment interest separate from the price, nor is it permissible to impose an increase on the debt if the buyer delays payment.