When thou shalt vow... thou shalt not be slack... — The three yearly feasts are mentioned by Rashi and the Rabbis as occasions for the payment of vows. (See 1 Samuel 1:21.) This precept is cited in Ecclesiastes 5:4, but with sufficient verbal variation to prevent its being called a quotation.
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