Leviticus 5:6 (KJV)

Or if a soul swear, pronouncing with his lips to do evil, or to do good, whatsoever it be that a man shall pronounce with an oath, and it be hid from him; when he knoweth of it, then he shall be guilty in one of these.

And it shall be, when he shall be guilty in one of these things, that he shall confess that he hath sinned in that thing:

And he shall bring his trespass offering unto the Lord for his sin which he hath sinned, a female from the flock, a lamb or a kid of the goats, for a sin offering; and the priest shall make an atonement for him concerning his sin.

And if he be not able to bring a lamb, then he shall bring for his trespass, which he hath committed, two turtledoves, or two young pigeons, unto the Lord; one for a sin offering, and the other for a burnt offering.

And he shall bring them unto the priest, who shall offer that which is for the sin offering first, and wring off his head from his neck, but shall not divide it asunder: