Is it permissible to take a sum of money from a merchant intermediary who invested my money, which I deposited with him as a trust, knowing that he guarantees the original amount and has divided the profit equally between us?

It is not permissible to repay a loan with more than its original amount if this increase was stipulated at the time of the loan or if there was a pre-arranged agreement for the increase. However, if there was no such condition or agreement, then there is no objection to repaying the loan with more than its original amount, and in a better quantity and quality, based on the Prophet's (peace and blessings be upon him) saying: "Indeed, the best among people are those who are best in repaying their debts."