What is the religious ruling on dealing with a person who insults the questioner and some members of his family with obscene language, and is it permissible to deter him by fighting?

Insulting, cursing, and humiliating a Muslim are forbidden and a grave sin, as the Prophet, peace and blessings be upon him, said: "Cursing a Muslim is فسوق (disobedience/impiety), and fighting him is disbelief," and "It is enough evil for a person to despise his Muslim brother." The insulter must repent and seek forgiveness. If he apologizes, accept his apology and forgive him. If he persists, be patient and counter his ill-treatment with kindness, seeking reward, in accordance with the Almighty's saying: "and those who restrain anger and pardon people," and "Repel [evil] with that which is better." We advise avoiding sitting with this person.