Is it permissible to abandon brothers in faith due to actions and words they utter that displease God, such as disobeying their mother, insulting sisters, oppressing wives, and coveting the wealth of sisters?

The legitimate shunning of a disobedient person is only permissible if its benefit outweighs its harm. The duration of shunning for one's own self should not exceed three days. It is obligatory to advise relatives with wisdom, vary the methods of da'wah (invitation to Islam), explain the religious ruling and offer admonition, and provide religious booklets and tapes. If that does not work, then shunning is permissible if it serves as a deterrent; otherwise, it is not.