Leviticus 5:4

If a soul swear — Rashly, without consideration either of God's law, or his own power or right, as David did, 1 Samuel 25:22. To do evil — To himself, to punish himself either in his body, or estate, or something else which is dear to him. Or rather to his neighbour. And it be hid from him — That is, he did not know, or not consider, that what he swore to do, was or would be impossible, or unlawful: When he discovers it to be so, either by his own consideration, or by information from others, whether it was good or evil which he swore to do.