Leviticus 5:4-6

4“Or suppose you make a foolish vow of any kind, whether its purpose is for good or for bad. When you realize its foolishness, you must admit your guilt.

5“When you become aware of your guilt in any of these ways, you must confess your sin.

6Then you must bring to the Lord as the penalty for your sin a female from the flock, either a sheep or a goat. This is a sin offering with which the priest will purify you from your sin, making you right with the Lord.