Riba

And that which you give in gift (loan) (to others), in order that it may increase (your wealth by expecting to get a better one in return) from other people’s property, has no increase with Allâh; but that which you give in Zakât (sadaqa - charity etc.) seeking Allâh’s Countenance, then those, they shall have manifold increase.

That they took riba (usury), though they were forbidden and that they devoured men’s substance wrongfully – We have prepared for those among men who reject faith a grievous punishment.