Does a divorce take effect when the husband says to his wife's grandfather, "By divorce, you are radiant today," three times, knowing that he did not intend divorce by that?

If the husband is truthful in his belief that the wife’s grandfather is enlightened (minawwar al-wajh), then divorce is not obligatory for him. However, if he is untruthful in his belief, then divorce is obligatory for him according to the majority of scholars. But, if the oath stems from his personal belief without it conforming to reality, then neither divorce nor an expiation for an oath is obligatory for him. The husband must avoid oaths of divorce, whether serious or in jest, so that he does not fall into undesirable consequences.