When thou shalt vow a vow unto the LORD thy God, thou shalt not slack to pay it: for the LORD thy God will surely require it of thee; and it would be sin in thee. When thou shalt vow, etc. - See on Numbers 30:2 (note), etc.
Related Commentaries of Deuteronomy 23:21
Deuteronomy 23:21
21 When thou shalt vow a vow unto the LORD thy God, thou shalt not slack to pay it: for the LORD thy God will surely require it of thee; and it would be sin in thee