A Woman Swore Not to Enter Her Son's House and (Now) She Wishes to Buy the House

Question :

A woman swore not to enter her son's house after his father died and (now) the mother wishes to buy the house and the son agrees. May the mother buy the house and live in it? And if it is not permissible for her, is there any atonement?

Answer:

There is no objection to her buying the house, if its owners agree to sell it. If she entered it after buying it, then there is no atonement incumbent upon her, because it has become her house, not the house of her son. But if she entered the house of her son in which he lives, she must make atonement for an unfulfilled oath, whether he owned the house or he rented it.

The atonement for an unfulfilled oath, or an oath which is not kept, is to feed ten poor persons, or to clothe them, or to free a slave. Whoever is unable to do these three things must fast for three (consecutive) days as proved by the Words of Allah, Most Glorified in Surat Al-Ma'idah. Each poor person is given half a Sa' of the staple food of the country, such as dates, rice or some other food; that is equivalent to approximately one and a half kilograms. If he fed them lunch or dinner, or clothed each of them with a garment suitable for praying in, that would be sufficient for him.

If her son was living in the house after she bought it and she entered before he had moved, she would have to make the aforementioned atonement.

And Allah is the Granter of success.

Source:
Ibn Baz
Fatawa Islamiyah, Vol. 6 Pages 384-385