| Rab-al-maal | In a mudaraba contract the person who invests the capital. |
| Riba | This term literally means an increase or addition. Technically it denotes any increase or advantage obtained by the lender as a condition of the loan. Any risk-free or "guaranteed" rate of return on a loan or investment is riba. Riba, in all forms, is prohibited in Islam. In conventional terms, riba and "interest" are used interchangeably. |
| Riba al Buyu | A sale transaction in which a commodity is exchanged for the same commodity but unequal in amount and the delivery of at least one commodity is postponed. To avoid riba-al-buyu, the exchange of commodities from both sides should be equal and instant. Riba-al-buyu was prohibited by the prophet Mohammad to forestall riba (interest) from creeping into the economy from the back door. |
| Riba al Fadl | Usury of trade. It is an alternative term for riba al-buyu. |
| Riba al Nasia | Increment on the principal of a loan payable by the borrower. It refers to the practice of lending money for any length of time on the understanding that the borrower would return to the lender at the end of this period the amount originally lent together with an increment in consideration of the lender having granted him time to pay. The increment was known as riba al-nasia. It was in vogue in Arabia in the days of the Prophet Muhammad. |
| Ruq'a | Banking instrument of the early Muslim period. It was a payment order to draw money from the bank. |
