Leviticus 5:1-4

And if anyone does wrong by saying nothing when he is put under oath as a witness of something he has seen or had knowledge of, then he will be responsible: If anyone becomes unclean through touching unconsciously some unclean thing, such as the dead body of an unclean beast or of unclean cattle or of any unclean animal which goes flat on the earth, he will be responsible: Or if he becomes unclean through touching unconsciously any unclean thing of man, whatever it may be, when it is made clear to him he will be responsible: Or if anyone, without thought, takes an oath to do evil or to do good, whatever he says without thought, with an oath, having no knowledge of what he is doing; when it becomes clear to him, he will be responsible for any of these things.