Is it necessary to fulfill a vow of obstinacy and anger until the expiation is paid, or does acting upon it become null and void upon the intention to pay it?

The one who makes a vow out of obstinacy or anger has the choice between fulfilling what he committed to or performing an expiation for an oath (kaffarat yamin). If he chooses the expiation, he must pay it immediately. He is not obligated to fulfill the vow before or after paying the expiation.

It is preferable to pay the expiation from one's private funds. If that is not possible, the one who made the vow must fast for three days.