How a sister should deal with her sister who is undutiful to her mother and does not accept advice

Question:
This questioner says to me: "My sister is undutiful to her mother, and when I try to advise her, she insults me and quarrels with me. She is the one who starts the quarrel. How should I deal with her, knowing that I speak to her very little, and she does not accept advice, and she sees herself as being on the straight path, whereas that is not the case?"

Answer:
You must offer advice with kind words and a good manner. Say: "O so-and-so, fear Allah. Being dutiful to your mother is one of the most important obligations. Be patient with her and treat her well with kind words and a good manner. O so-and-so! O my sister so-and-so! Fear Allah, and be mindful of Allah, even if she gets angry, or even if she is not pleased. For Allah says: [Surat al-Tawbah: 71]. Her undutifulness to her mother is what is wrong, and you, if Allah wills, are among the believers, so disavow her of it, and teach her with a good manner and kind words. If it is possible, advise some of your relatives to advise her, such as her brothers, or her maternal uncles, or her father if he is still alive, so that they advise her along with you, and help you with her. Yes.

The presenter: May Allah reward you, Your Eminence.