Is the financial amount I obtained from a university loan—amounting to fifteen thousand euros, with ten thousand euros only required to be repaid and the possibility of keeping five thousand euros, and with interest to be paid in case of late repayment—considered unlawful money? And does its unlawfulness include the entire amount, or only the ten thousand euros that must be repaid? And is it permissible to continue taking this loan?

It is not permissible for the lender and borrower to agree upon an increase in exchange for delay in repayment, because it is usury (riba). Repentance from this forbidden contract is necessary. The borrowed money is permissible for the borrower, despite the sin of usury. One must be diligent in repaying the loan on time to avoid paying actual usury and the threat against the "one who commissions usury." The surplus money that can be kept is a gift, and there is no harm in benefiting from it.