What is the Sharia ruling on swearing an oath of divorce conditioned on not renting out the apartment, and does the divorce occur if it is rented out?

The relied-upon opinion is that swearing by divorce results in divorce upon breaking the oath, regardless of whether the one who swore intended to effect it or merely to threaten. Accordingly, if he rented the apartment, his divorce has occurred. If he had not divorced his wife more than once before, he may rent the apartment, and one divorce will be counted against him. He may then take his wife back before her 'iddah (waiting period) expires. It must be known that the permissible oath is swearing by Allah Almighty, whereas swearing by divorce is among the oaths of the wicked.