A vow is a promise or pledge a person makes to someone else. For example, when a man and woman get married, they make vows to each other. They promise to love each other as long as they live.
Also, a vow is a promise a person makes to God (see: Psalm 50:14; 56:12; Acts 18:18). When someone does this, they promise to do a certain thing in order to greatly honor God. Sometimes a person vows to do something if God will do something that helps that person (see: 1 Samuel 1:11).
After a person makes a vow, that person must keep or fulfill the vow. That is, a person must do what that person promised to do. The Bible teaches that God may judge the person who does not keep one’s own vow.
In the Old Testament, people sometimes offered sacrifices when they made vows to God (see: Leviticus 7:16; Numbers 15:8). Nazarite vows are an example of a vow a person makes, promising to serve God in a special way (see: Numbers 6:1-21; See also: Judges 13:5).
The Bible warns people to think carefully before making a vow. It is better to not make a vow rather than to make a vow and not keep it (see: Proverbs 20:25; Ecclesiastes 5:4-5; 1 Timothy 5:11-15). Jesus also warned people about making vows. Jesus said it is better for people to do what they say they will do rather than to make a vow (see: Matthew 5:33-37).