Is it permissible to work on installing ATMs for a non-Islamic bank, knowing that the salary comes from the company and not from the bank, and that the company is not responsible for the financial transactions between the bank and commercial establishments?

It is not permissible to assist usurious institutions, even through indirect service, due to Allah’s saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." The Hadith indicates that the warning includes everyone who assists in usury, and installing devices for these usurious banks falls under this assistance. Therefore, it is not permissible to do so. The fact that the salary comes from another source is not influential, as the consideration is the work itself and what results from it in terms of assisting usurious banks.