What is the ruling on a husband swearing an oath of divorce, saying, "My wife is divorced from me if my father sells the piece of land and distributes the inheritance during his lifetime," and is expiation incumbent upon him if his father does so?

The view held by the majority of scholars is that whoever swears an oath by divorce and then breaks it, their divorce takes effect, whether they intended to initiate the divorce or merely to threaten or emphasize. However, Sheikh al-Islam Ibn Taymiyyah holds the view that if one swears an oath by divorce for the purpose of threat or emphasis, they are only liable for an expiation for an oath (kaffarat yamin) and the divorce does not take effect if they break their oath.

Therefore, according to the preponderant opinion (al-mufta bihi), your husband's father's divorce will take effect if he sells the land and divides his properties. If this divorce does not complete the three divorces, then your husband may reconcile with you during your waiting period (iddah). However, according to the opinion of Sheikh al-Islam Ibn Taymiyyah, if he did not intend to initiate divorce but merely to threaten, then his divorce does not take effect, but he is liable for an expiation for an oath.

It should be noted that the lawful oath is to swear by Allah the Almighty, and swearing by divorce is among the oaths of the dissolute.