Ruling on student loans based on takaaful where the individual pays back more than he borrowed in order to help other students

Stipulating that an additional amount be repaid when repaying
a loan comes under the heading of riba (usury) concerning which there is no
difference of scholarly opinion that it is prohibited. 

It says in Fataawa al-Lajnah ad-Daa’imah (2/11/111): 

Stipulating that an additional amount be repaid on a loan is
blatant riba, because the Prophet (blessings and peace of Allah be upon him)
said: “Every loan that brings a benefit is riba.” And the scholars are
unanimously agreed on that. End quote. 

There is no difference in the ruling regardless of whether
the stipulated additional amount will go back to the lender or to someone
else, because it is an additional amount stipulated in the loan contract,
therefore it is riba in either case. Shaykh ‘Ulaysh al-Maaliki said in
Fath al-‘Aliy al-Maalik fi’l-Fatwa ‘ala Madhhab al-Imam Maalik
(1/363): 

The fourth issue: with regard to conditions having to do with
the loan, they fall into three categories: a category which renders the loan
invalid; a category that does not render the loan invalid and must be
fulfilled; and a category concerning which there is a difference of
scholarly opinion. 

The first category includes everything that brings a benefit
to someone other than the borrower, whether it benefits the lender or
someone other than the lender or the borrower. End quote. 

If the borrower wants to benefit other students, it is
permissible for him to return the loan with something extra, as a voluntary
donation on his part, without that being stipulated in the contract, because
returning a loan with something extra that was not previously stipulated is
permissible, because it comes under the heading of paying off loans
properly, and is not riba. 

This has been discussed previously in fatwa
148458. 

And Allah knows best.