What is the ruling on a loan taken from an interest-based bank, and what must the borrower do after his father prevented him from repaying part of the debt and ordered him to buy a car for his brother with that amount?

"Taking a loan with interest is forbidden (haram). The one who does so must repent and seek forgiveness. He must return the borrowed amount without interest if possible. Otherwise, he should pay the interest, and the sin is on the one who forced him into it. As for your father's request to prioritize the purchase of a car for your brother over paying off your debt, you are not obligated to fulfill it. However, fulfilling it is better if the debt is not due immediately or if it does not lead to a delay in repayment."