Does a divorce occur from a husband who swears an oath using the phrase "upon me be divorce" (عليّ الطلاق), believing it to be merely an oath or a threat, and not a conditional divorce, based on the prevailing custom in his environment that considers it idle talk, knowing that he is educated and cultured?

The permissible oath is to swear by Allah the Almighty. As for swearing by divorce, it is among the oaths of the dissolute. Scholars have differed regarding its ruling, between prohibition and detestability. The majority of scholars hold that swearing by divorce or making it conditional upon an event triggers divorce, whether the intention was divorce, threat, prevention, encouragement, or emphasis. However, some scholars, such as Sheikh Al-Islam Ibn Taymiyyah, are of the opinion that whoever swears by divorce or makes it conditional upon an event without intending divorce, then expiation for an oath is due upon him, and no divorce occurs. There is no blame upon a layperson for acting upon the opinion of some scholars as long as he is comfortable with the soundness of the opinion.