What is the ruling on someone who swore not to commit a haram act for a month, and then during that month swore to commit it? And is expiation (kaffarah) required if he commits it?

Abandoning the forbidden is an obligation throughout life. Whoever swears to abandon it and then commits it has broken his oath, and expiation becomes obligatory upon him. As for whoever swears to commit the forbidden, he is considered disobedient and must break his oath and offer expiation for it, because persisting in this state is a sin.