Is the husband obligated to obey his mother in divorcing his wife without cause, and does the mother sin if she unjustly demands the divorce of the wife?

A woman's belonging to a specific group is not a criterion for classification or preference, as people are equal and the criterion for preference is piety (taqwa). The husband must honor his mother and obey her in what is right and lawful, but she does not have the right to ask him to divorce his wife, and he is not obligated to respond to her request. The mother would be sinful if she caused a divorce without a valid reason, because Islamic law has forbidden seeking divorce without a valid reason.