Are debtors who fail to fulfill their promises of repayment considered hypocrites, and is it permissible for the creditor not to forgive them after their death?

Breaking a promise without a valid excuse is a sign of practical hypocrisy (nifaq 'amali), not the hypocrisy of disbelief (nifaq kufr). If the debtor is in straitened circumstances, this does not apply to him. It is forbidden for a wealthy person to procrastinate in repaying a debt. The creditor has the right to demand his debt and is not obligated to forgive it. The debt of a deceased person is to be paid from his estate before its distribution.