What is the ruling on working in usurious banks given the family problems that result from it, and how can one convince the father to leave this job?

It is not permissible to work in usurious banks, due to witnessing evil therein and cooperating in sin, and because the Prophet, peace and blessings be upon him, cursed the one who consumes usury, the one who feeds it, its scribe, and its two witnesses. Obedience to the parent is not obligatory in this matter, for obedience is only in what is good, "There is no obedience to a creature in disobedience to the Creator." Therefore, try to convince your father with wisdom and gentleness, while being good and dutiful to him.