"You shall not be to him as a creditor"—Exodus 22:24.
It is forbidden to demand payment of a debt from a borrower if the lender is aware that the borrower has not the means to repay. It is even forbidden for the lender to pass before the borrower [lest his presence, and therefore the acute awareness that he owes him money, shame him].
Demanding repayment of a debt that includes interest is also included in this prohibition.
