Interest (Riba) is Prohibited

Allah prohibits His believing servants from dealing in Riba and from requiring interest on their capital, just as they used to do during the time of Jahiliyyah. For instance, when the time to pay a loan comes, the creditor would say to the debtor, "Either pay now, or the loan will incur interest." If the debtor asks for deferment of the loan, the creditor would require interest and this would occur year after year until the little capital becomes multiplied many times. Allah also commands His servants to have Taqwa of Him so that they may achieve success in this life and the Hereafter. Allah also threatens them with the Fire and warns them against it, saying,

وَاتَّقُواْ النَّارَ الَّتِى أُعِدَّتْ لِلْكَـفِرِينَ - وَأَطِيعُواْ اللَّهَ وَالرَّسُولَ لَعَلَّكُمْ تُرْحَمُونَ

Commentary

In the previous verse, Muslims were commanded to abstain from interest-based dealings, a sin which deprives them of the quality of Taqwa, (the fear of Allah, the sense of responsibility before Him).