What is the ruling on working for companies where part of their work is permissible and part is impermissible, such as: companies that export materials to Muslim and hostile countries, construction companies that establish projects including permissible and impermissible places (like liquor stores), university libraries that contain books teaching forbidden matters (like usury and commercial insurance), and pharmaceutical companies that produce abortion drugs or drugs containing pork derivatives? And what is the ruling on dealing with these companies if one establishes a private company?

Working in companies with mixed fields (halal and haram) is permissible if the worker does not engage in the forbidden field, such as producing a forbidden medicine or designing a place for disobedience. As for things that can be used for both permissible and forbidden purposes, it is permissible to manufacture and sell them to the general public unless it is known that they will be used for disobedience or in a war against Muslims. Preparing research on investment opportunities for a usurious bank is considered assisting in what is forbidden, according to the verse: "And do not cooperate in sin and aggression."