Leviticus 5:4-5
4
"'Or if anyone swears rashly with his lips to do evil, or to do good, whatever it is that a man might utter rashly with an oath, and it is hidden from him; when he knows of it, then he shall be guilty of one of these.
5
It shall be, when he is guilty of one of these, he shall confess that in which he has sinned: