Leviticus 5:1, 4

‘Now if a person sins after he hears a public order 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 punishment.

Or if a person swears thoughtlessly with his lips to do evil or to do good, in whatever matter people speak thoughtlessly with an oath, and it is hidden from him, and then he comes to know it, he will be guilty of one of these things.