538. Covenant to pay on or on or after a certain day.

Where a day for payment is fixed by the mortgage covenant1, the right to claim arises upon non-payment on that day, as the affirmative covenant implies that the lender will not sue before that day2. Consequently, a substituted covenant taken by the mortgagee for payment at a date subsequent to that originally fixed is a binding arrangement to give time, and ordinarily discharges a surety3. If the covenant also fixes a place for payment, the creditor must attend there to receive payment, and there is no default unless he does so4. The claim on the covenant is for principal