Matthew 5:33

Deuteronomy 23:21 NIV
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.

Ecclesiastes 5:4-6 NIV
When you make a vow to God, do not delay to fulfill it. He has no pleasure in fools; fulfill your vow. It is better not to make a vow than to make one and not fulfill it. Do not let your mouth lead you into sin. And do not protest to the temple messenger, “My vow was a mistake.” Why should God be angry at what you say and destroy the work of your hands?

Leviticus 19:12 NIV
“‘Do not swear falsely by my name and so profane the name of your God. I am the Lord.