Leviticus 5:4-6

MLV(i) 4 Or if a soul swears rashly with his lips to do evil, or to do good, whatever it is that a man will utter rashly with an oath and it is hid from him, when he realizes it, then he will be guilty in one of these.
5 And it will be, when he will be guilty in one of these, that he will confess that by which he has sinned. 6 And he will bring his trespass offering to Jehovah for his sin which he has sinned, a female from the flock, a lamb or a goat, for a sin offering. And the priest will make atonement for him as concerning his sin.