Leviticus 5:1-2
Additional Sin Offering Regulations
5:1 “‘When a person sins in that he hears a public curse against one who fails to testify and he is a witness (he either saw or knew what had happened) and he does not make it known, then he will bear his punishment for iniquity.
5:2 Or when there is a person who touches anything ceremonially unclean, whether the carcass of an unclean wild animal, or the carcass of an unclean domesticated animal, or the carcass of an unclean creeping thing, even if he did not realize it, but he himself has become unclean and is guilty;