Is a person considered disobedient to their parents if they laugh upon seeing their sister provoke or quarrel with their mother, causing the mother to become angry?

The rights of parents are great. If your laughter at your sister's actions harms your mother, grieves her, and makes her think that you are gloating over her, then it is feared that this could be an act of disobedience. You must advise your sister and admonish her for her mistreatment of your mother.