What is the ruling on shunning a person because his family is not speaking to him or is in dispute with him, whether he is a relative or a stranger, and what is obligatory to do in such a case?

A Muslim's abandonment of his brother for more than three days without a legitimate شرعي reason is forbidden (haram). The prohibition is further emphasized if the one abandoning is a relative (dhu rahim). A person's disagreement with someone's family members does not justify abandoning that person. It is incumbent upon anyone aware of such abandonment to advise the one abandoning, explain the impermissibility (hurmah) of mutual abandonment, remind him of Allah, and call him to repentance.