Ecclesiastes 5:4-6

4When you make a vow or a pledge to God, do not put off paying it; for God takes no pleasure in fools [who thoughtlessly mock Him]. Pay what you vow.

5It is better that you should not vow than that you should vow and not pay.

6Do not allow your speech to cause you to sin, and do not say before the messenger (priest) of God that it was a mistake. Why should God be angry because of your voice (words) and destroy the work of your hands?