What is the ruling on dealing with a brother who is disobedient to his parents, raises his voice at them, and does not accept advice, given that he is the only male in the household besides the questioner?

The brother committed a grave error by raising his voice and responding harshly to his parents. The rights of parents are immense, second only to the rights of Allah and His Messenger. Allah Almighty has linked beneficence to them with His worship, and He has forbidden even saying "uff" to them or repelling them, and He has commanded kind words to them and to lower the wing of humility to them. The Prophet, peace and blessings be upon him, considered disobedience to parents to be among the gravest major sins. The brother must repent, and the questioner should advise him gently and with kindness towards his parents, using a good approach and quoting verses and hadiths. He should also seek righteous companions for him and distance him from bad companions, encourage him to attend circles of knowledge and listen to beneficial lectures, and make abundant supplications for him.