What should a young man do who works for a contracting company and is looking for new projects, if he finds a project to build a bank tower, and he fears that reporting about the project and his company's cooperation in building it would be a form of cooperation in sin and aggression, while at the same time he fears sin if he does not report it and considers that a dereliction of duty and a failure to fulfill his trust?

Dealing with usury is forbidden and is one of the major sins. The Messenger of Allah, may Allah bless him and grant him peace, cursed the one who consumes usury, the one who pays it, its scribe, and its two witnesses. It is not permissible to cooperate in sin and aggression. Therefore, it is not permissible to establish usurious banks, equip them, or assist them. Thus, it is not permissible for you to guide the company to build a usurious bank, because this is cooperation in sin, and it is not a dereliction of duty but rather advice to the company. As for Islamic banks, there is no harm in establishing them or guiding others to them.