If my sister works in a bank, is it permissible for me to wear her clothes?

If your sister works in a non-usurious bank, then her work is permissible and her money is lawful, and you may benefit from it. However, if she works in a usurious bank, then her work is forbidden and the money earned from it is forbidden. But there is no objection to using her clothes with her permission, because the prohibition relates to her responsibility, not to what she purchased. Ibn Rushd mentioned that the forbidden is attributed to the responsibility of the seller and the giver of the gift.