What is the ruling on divorce if the husband swore to his mother that his wife would be divorced if she asked about her?

If a husband swears by Allah that he will divorce his wife if her mother inquires about her, he is not obligated to divorce her if her mother inquires about her; instead, he must offer expiation for a broken oath (kaffarat yamin). However, if he makes the divorce conditional on her mother inquiring about her, the fatwa we follow states that the divorce takes place if the mother inquires, whether the husband intended to make the divorce conditional or merely to threaten. If the divorce occurs and it is not the third divorce, the husband may take her back before the 'iddah (waiting period) expires. Some scholars are of the view that a conditional divorce intended as a threat or for emphasis does not constitute a divorce; rather, the husband is obligated to offer expiation for a broken oath if the condition is met.