Leviticus 5:4-6

Complete Jewish Bible

⁴ If someone allows to slip from his mouth an oath to do evil or to do good, and he doesn’t remember that he clearly spoke this oath, then, no matter what it was about, when he learns of it, he is guilty. ⁵ A person guilty of any of these things is to confess in what manner he sinned ⁶ and bring his guilt offering to Adonai for the sin he committed; it is to be a female from the flock, either a lamb or a goat, as a sin offering; and the cohen will make atonement for him in regard to his sin.