Leviticus 5:3-5

3Or if he touches human uncleanness  — any uncleanness by which one can become defiled  — without being aware of it, but later recognizes it, he incurs guilt.

4Or if someone swears rashly to do what is good or evil — concerning anything a person may speak rashly in an oath — without being aware of it, but later recognizes it, he incurs guilt in such an instance.

5If someone incurs guilt in one of these cases, he is to confess he has committed that sin.