The Cow - 2:278
O you who believe, if you really believe, listen to Allah and abandon all forms of usury.
Related:
The Cow/2:188
Do not eat your money unjustly among yourselves. And do not bribe officials/managers with the intention of taking the people´s money unjustly.
The Women/4:29
Believers! Do not eat one another´s property by injustice and deceit, even in consensual trade. Do not kill one another. Allah is Most Merciful to you
The Romans/30:39
The usury money which you give to increase in the wealth of the people does not increase with Allah. But as for the zakat which you give seeking Allah´s Pleasure, those who give it multiply their investment.