Does working in banks involve usury, or is usury limited to a specific part of banking, and how can one distinguish between usurious and non-usurious banks, and what is the ruling on working in Bank AlJazira in Saudi Arabia?

It is not permissible to work in a usurious bank in any form whatsoever, because it constitutes cooperation in sin and aggression. A usurious bank is one that deals with usury in lending, borrowing, and investing. An example of this is when the bank commits to a known percentage of the capital for the investor or the deposit holder, such as 10%, for this is the very essence of usury.