Leviticus 5:1-7

“If anyone sins in that he hears a public adjuration to testify, and though he is a witness, whether he has seen or come to know the matter, yet does not speak, he shall bear his iniquity; or if anyone touches an unclean thing, whether a carcass of an unclean wild animal or a carcass of unclean livestock or a carcass of unclean swarming things, and it is hidden from him and he has become unclean, and he realizes his guilt; or if he touches human uncleanness, of whatever sort the uncleanness may be with which one becomes unclean, and it is hidden from him, when he comes to know it, and realizes his guilt; or if anyone utters with his lips a rash oath to do evil or to do good, any sort of rash oath that people swear, and it is hidden from him, when he comes to know it, and he realizes his guilt in any of these; when he realizes his guilt in any of these and confesses the sin he has committed, he shall bring to the LORD as his compensation for the sin that he has committed, a female from the flock, a lamb or a goat, for a sin offering. And the priest shall make atonement for him for his sin. “But if he cannot afford a lamb, then he shall bring to the LORD as his compensation for the sin that he has committed two turtledoves or two pigeons, one for a sin offering and the other for a burnt offering.