Deuteronomy 23:21

21 If you make a vow to the LORD your God, do not be slow to pay it, for the LORD your God will certainly demand it of you and you will be guilty of sin.

Read Deuteronomy 23:21 Using Other Translations

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
"If you make a vow to the LORD your God, you shall not delay fulfilling it, for the LORD your God will surely require it of you, and you will be guilty of sin
“When you make a vow to the LORD your God, be prompt in fulfilling whatever you promised him. For the LORD your God demands that you promptly fulfill all your vows, or you will be guilty of sin.