What is the ruling on a daughter helping her father transfer his usurious money and interest from a usurious bank to an Islamic bank, knowing that he gets angry if his daughter does not help him and he trusts no one but her?

Helping a father transfer his money from an interest-based bank to a non-interest-based one is not sinful; rather, it is desirable. Obedience to him is obligatory if he requests that, and there is no harm in processing the paperwork on his behalf. He should be alerted to the impermissibility of benefiting from usurious gains and the necessity of disposing of them by spending them on Muslim welfare, while observing politeness and gentleness when enjoining good and forbidding evil.