Quran and Sunnah are two major sources of Shariah which form the basis of Islamic finance. Below are some verses from the Holy Quran related to the prohibition of Riba (usury/interest):
(1) Those who eat Riba (usury) will not stand (on the Day of Resurrection) except like the standing of a person beaten by Shaitan (Satan) leading him to insanity. That is because they say: "Trading is only like Riba (usury)," whereas Allah has permitted trading and forbidden Riba (usury). So whosoever receives an admonition from his Lord and stops eating Riba (usury) shall not be punished for the past; his case is for Allah (to judge); but whoever returns (to Riba (usury)), such are the dwellers of the Fire - they will abide therein.
( سورة البقرة , Al-Baqara, Chapter #2, Verse #275)
(2) Allah will destroy Riba (usury) and will give increase for Sadaqat (deeds of charity, alms, etc.) And Allah likes not the disbelievers, sinners.
( سورة البقرة , Al-Baqara, Chapter #2, Verse #276)
(3) O you who believe! Be afraid of Allah and give up what remains (due to you) from Riba (usury) (from now onward), if you are (really) believers.
( سورة البقرة , Al-Baqara, Chapter #2, Verse #278)
(4) O you who believe! Eat not Riba (usury) doubled and multiplied, but fear Allah that you may be successful.
( سورة آل عمران , Aal-e-Imran, Chapter #3, Verse #130)
(5) And their taking of Riba (usury) though they were forbidden from taking it and their devouring of mens substance wrongfully (bribery, etc.). And We have prepared for the disbelievers among them a painful torment.
( سورة النساء , An-Nisa, Chapter #4, Verse #161)
Are we on the right tract?