What is the Shar'i ruling regarding a husband who utters inappropriate words towards his wife's mother, who resides with them in the house, and what should the wife do about this?

The husband should be thanked for his act of accommodating the wife's mother at his expense, as it is not obligatory for him. However, this good deed should not be ruined by boasting or causing harm. The husband should know that showing kindness and dutifulness to the wife's mother is a form of kindness and honor towards the wife herself. He must refrain from anything that might hurt his mother-in-law's feelings or disturb her serenity, and he will be rewarded for this if he intends it for the sake of Allah. We advise the wife to explain the matter to her husband with wisdom and gentleness, present the fatwa to him, and avoid reproaching him or using harsh words with him.