Leviticus 5:4-7

4Or if a soul shall make an oath, pronouncing with his lips to do evil, or to do good, whatever it may 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. 5And it shall be, when he shall be guilty in one of these things, that he shall confess that he hath sinned in that thing : 6And he shall bring his trespass offering to 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.

7And if he shall not be able to bring a lamb, then he shall bring for his trespass, which he hath committed, two turtledoves, or two young pigeons, to the LORD; one for a sin offering, and the other for a burnt offering.1