Customarily if the loan or interest or taxes be not paid, the lender seeks relief by foreclosing the mortgage upon the land, as in this action he can not only enforce the mortgage against the security but may ask for judgment upon the bond, in case the amount realized upon the sale of the land be not sufficient to satisfy his claim. However the bond is an instrument for the payment of money, and nothing prevents the lender suing upon the bond, without regard to the mortgage. If a judgment in such action will not enable the lender to collect his claim, he may then, upon permission of the court, sue to enforce the mortgage by foreclosure.