Is Any Benefit from a Loan Prohibited in Islam?
It is a well-established rule in the Shariah (Islamic law) that a loan contract is of a charitable nature and as such the lender may not stipulate any excess or benefit from the borrower. However, it is also known in the Shariah that if the benefit from a loan comes to the lender voluntarily and it is not stipulated in the loan contract then it is permissible. This exception derives from some reports that the Prophet used to repay his debt with some increment, and to this effect he said: "The best amongst you are those who benevolently repay their debts”.