Is the interest gained from the bank or from a loan taken from it permissible or forbidden?

Borrowing from a bank with interest is forbidden because it is usury (riba), which is prohibited by Islamic law. Usury is a declaration of war from Allah and His Messenger. Similarly, investing money in usurious banks is forbidden because it is either usury itself or an aid to it. Whoever repents after having taken interest must dispose of it by spending it on general Muslim welfare, and it is not permissible for him to own it.