Leviticus 5:4-6

Amplified Bible

⁴ Or if anyone swears [an oath] thoughtlessly or impulsively ^[a]aloud that he will do either evil or good, in whatever manner a person may speak thoughtlessly or impulsively with an oath, but he is unaware of it, when he recognizes it, he will be guilty in one of these.^{(A) 5} So it shall be when a person is guilty in one of these, that he shall confess the sin he has committed. ⁶ He shall bring his guilt offering to the Lord for the sin which he has committed, a female from the flock, a lamb or a goat as a sin offering. So the priest shall make atonement on his behalf for his sin.