What should a married sister, who wears the Shar'i hijab and is not convinced by the niqab, do when her husband's mother insists she wear the niqab and threatens to be angry with her son because of her?

We believe that the sister must obey her husband's mother in matters of goodness she commands, such as covering the face, even if she is not convinced of its obligation. Covering the face is obligatory according to the most preponderant opinion among scholars, and her covering her face removes her from dispute, safeguards her religion, and pleases her husband's mother. As for the husband's mother's anger at her son because of his wife, there is no sin upon her in that, but since she is the cause, she should strive to reconcile between them and earn the husband's mother's satisfaction by complying with her command; this is a form of honoring the husband and good companionship.