Is it permissible to divorce one's sister from her husband due to his disobedience to his father and his severing of ties of kinship?

Your sister's husband, if he is disobedient and severs ties of kinship, has committed two great evils, as both are major sins. It is not permissible for you to seek to divorce your sister from him, as this is a type of corruption forbidden by Islamic law, based on the saying of the Prophet, peace and blessings be upon him: "He is not one of us who incites a woman against her husband."

If your sister desires to separate from him and requests a divorce, she is permitted to do so, because the husband's transgression is one of the justifications for seeking divorce. It should be noted that divorce may not always be the best option, especially with the presence of children, and one should be deliberate in seeking it unless its benefit outweighs its harm.

It is recommended to supplicate for his guidance and to continue advising him gently and kindly. It is preferable that the advice come from someone who holds a respected position in his eyes.