Sforno on Deuteronomy 23:22/ספורנו על דברים כ״ג:כ״ב

1כי תדור נדר לה' אלוקיך, you are, of course, expected to honour your undertakings without reinforcing them in the form of a vow or oath. When you made a vow to G’d, however, not only are you obligated to pay up, but the payment must be made without undue delay.

2כי דרוש ידרשנו, He will demand it of you,

3 so that if that becomes necessary you are already guilty of a sin of omission.