Repaying loans with excess on one side
In the name of Allah, the most Beneficent, the most Merciful.
Asking for a loan or taking a loan is permissible as long as one has the intention & means of paying it back. If a person took a loan without the intention to pay it back, then one will be consuming unlawful wealth. (Sahih Bukhari p.321 v.1 & Fatawa Hindiyyah p.366 v.5)
In regards to your question it is recommended (mustuhub) to pay something more when returning the loan. This however, should be done out of one’s own will, and not enforced. If it is forced on someone to pay an extra amount on the top of the amount borrowed, then this will be classed as riba, thus unlawful.
It is narrated by Saaiduna Abu Hurairah (RA) that the Prophet of Allah Sallallahu Alahi Wasalam said; “The best amongst the people is he who repays his debt in the most handsome manner.” (Sahih Bukhari p.322 v.1)
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham.