Giving extra money to a lender without obligation

Mahdi Hossain via email,

Question: I borrowed some money from someone, but there was no contract or agreement for an additional return. Considering that I had utilised their funds, I willingly contributed an additional sum to the repayment. Is it acceptable to offer and receive this extra sum?

Answer: If there was no previous condition, express demand, concealed expectation, or social pressure involved, it is acceptable to give an additional sum upon repayment. However, any additional money paid or received under pressure or obligation is subject to the interest of Riba.

Answered by: Allama Mufti Obaydullah Rahman Khan Nadwi.

Source: Jame’ul Fatawa, Islamic Fiqh and Fatwa Encyclopedia