The Ruling on Swearing to Divorce and Swearing to do What is Forbidden

Question :

People in our area frequently swear oaths to divorce and to make their wives unlawful to them; what is the ruling on this?

Answer:

As for an oath to divorce, it is detested and it should not be done. It leads to family breakups according to some of the scholars and because divorce is the most hated of all permissible things to Allah.

So it is incumbent upon the Muslim to guard his tongue against this, except when it is necessary to divorce, and to resolve upon it when one is not in a state of anger.

It is more fitting to content oneself with swearing by Allah, Most Glorified, if a person wishes to emphasize something to one of his companions, or to one of his guests, to make him stay with him or anything else. As for being angry, he should seek refuge with Allah from Satan and guard his tongue and his limbs from doing things that are not fitting. As for declaring something forbidden, it is not permissible, whether it was by way of an oath or anything else, according to the Words of Allah, Most High:
"O Prophet! Why do you forbid (for yourself) that which Allah has allowed to you."

as well as other well known evidences, and because it is not permissible for a Muslim to declare something forbidden if Allah has declared it permissible for him. May Allah protect us all from the prompting of Satan.

Source:
Ibn Baz
Fatawa Islamiyah, Vol. 6 Pages 385-386