Leviticus 5:1-7

If you sin: by not providing information after hearing a public solemn pledge even though you are a witness, knowing something, or having seen something so that you become liable to punishment; or by touching some unclean thing—the dead body of an unclean wild animal, unclean livestock, or unclean swarming creature—but the fact goes unknown so that you become unclean and guilty of sin; or by touching human uncleanness—any uncleanness that makes one unclean—and the fact goes unknown, but you later learn of it and become guilty of sin; or by carelessly swearing to do something, whether bad or good—whatever one might swear carelessly—and the fact goes unknown, but you later learn of it and become guilty of sin concerning one of these things— at that point, when you have become guilty of sin in one of these ways, you must confess how you have sinned and bring to the LORD as compensation for the sin that was committed a female from the flock, either a sheep or goat, as a purification offering. The priest will then make reconciliation for you, to remove your sin. If you can’t afford an animal from the flock, you can bring to the LORD as compensation for your sin two doves or two pigeons, one as a purification offering and the other as an entirely burned offering.