Leviticus 5:1-2

‘Now if a person sins after he hears a public adjuration to testify when he is a witness, whether he has seen or otherwise known, if he does not tell it, then he will bear his guilt. Or if a person touches any unclean thing, whether a carcass of an unclean beast or the carcass of unclean cattle or a carcass of unclean swarming things, though it is hidden from him and he is unclean, then he will be guilty.