Usury in the Koranic verses
In the Islamic traditions and koranic verses usury is seriously forbidden:
1. Those who live off interest on loans will never stand up, except in the way those whom Satan knocks down with a fit rise up again. That is because they say: “Trading is just like taking interest.” Yet Good has permitted trading and for bidden taking interest. Anyone receives such an instruction from his Lord and stops doing so, may keep whatever [capital] is a thing of the past. While his case rests with God; yet those who do so over and over again will become inmates of the fire, to remain there forever.(2:275)
2. God wipes out usury and nourishes acts of charity; God does not love every vicious disbeliever. (2:276)
3. You who believe, heed God and write off anything that remains outstanding from lending at interest if you are [true] believers. (2:278)
4. If you do not so, then be prepared to face war declared by God and his messenger! If you repent, you may retain you principal. Do not wrong [others] and you will not be wronged. (2:279)
5. You who believe do not live off usury which is compounded over and over again. Heed God so that you may prosper. Heed the Fire which has prepared for disbelievers. (3:130-131)
6. Because of wrong doing on the part of those who are Jews, we have forbidden them certain wholesome things which had been permitted them. And because they blocked off so many people from Gods way and took usury although they had been forbidden to and idly consumed over peoples wealth, we have reserved painful torment for those among them who are disbelievers.(4:160-161)
7.Any usury you farm out so it will be increased from(other) peoples wealth will never increase so far as God is concerned, while those of you who pay something as welfare tax while you seek Gods face , will have it multiplied.( 30:39)
Sources :
Nemuneh Koranic Exegesis (Naser Makarem)
The Noble Koran (English translation by T.B.Irving)