Usury Prohibited*
[3:130] O you who believe, you shall not take usury, compounded over and over. Observe GOD, that you may succeed.
*3:130 Interest on bank deposits and interest charged on loans are lawful if they are not excessive (5-15%). Banks invest and their profits are passed on to the depositors. Since all parties are happy and no one is victimized, it is perfectly lawful to take interest from the bank (see 2:275).
[3:131] Beware of the hellfire that awaits the disbelievers.
[3:132] You shall obey GOD and the messenger, that you may attain mercy.
Usury is not so much about the percentage, but the terms of the loan, i.e. what happens if the debtor cannot pay? Is the debtor being exploited or taken advantage of?
[2:278] O you who believe, you shall observe GOD and refrain from all kinds of usury, if you are believers. [2:279] If you do not, then expect a war from GOD and His messenger. But if you repent, you may keep your capitals, without inflicting injustice, or incurring injustice.