What is the legal ruling on someone who took an interest-free loan from his employer and then requested the cancellation of its installments after paying half of it?

Borrowing without usurious interest is permissible. It is also permissible for the borrower who is in straitened circumstances to request a delay [in repayment] or for the debt to be waived. It is stated in the Hadith: "Whoever grants a respite to one in straitened circumstances or waives [the debt] for him, Allah will shade him in His shade." It is a condition that the manager be authorized to discharge the debtor.