Is it permissible to work as a factory manager for granite production if the products will be used in projects of a forbidden nature, such as usurious banks, hotels that serve alcohol, commercial insurance companies, or co-educational schools, based on work orders that specify the name of the project, contractor, or exhibition? And is it obligatory to investigate the nature of the project when a work order is received under only the contractor's name? And does the factory management's refusal to investigate justify rejecting this job?

It is forbidden to deal with those who commit sins if such dealings assist them in their wrongdoing, based on the Almighty's saying: "And do not cooperate in sin and aggression." Thus, if it is known that a building will be allocated for a usurious bank, a commercial insurance company, or a hotel where Munkarat (reprehensible acts) are practiced, then it is impermissible to sell the materials used in its construction, nor is it permissible to work in a factory if it entails assisting in sin. However, if the work has no relation to the unlawful, then there is no issue with it.

Selling an item to someone who will use it for both permissible and impermissible purposes is not prohibited, unless it is known or highly probable that the building will be used for impermissible purposes. There is no obligation to investigate the buyer's intention. It is advised to seek what is lawful and avoid what is unlawful.