Is working at the National Commercial Bank permissible and lawful, given that it is an Islamic bank, or not?

It is permissible to work in Islamic banks that adhere to Sharia rules, such as Al-Rajhi Bank and Bank Al-Bilad, and in banks that are seriously transforming into Islamic banks, provided they commit to the decisions of the Sharia board. It is forbidden to work in interest-based (riba-based) banks, or in the interest-based departments of banks that operate Islamic windows. As for working in Islamic windows, it depends on the Sharia-based interest: some permit it to encourage Islamic dealings, while others believe it lends legitimacy to the interest-based bank. The ruling varies with time; in the beginning of Islamic banking, its encouragement was necessary. However, after the availability of sufficient Islamic banks, it is not permissible to work in interest-based banks under the pretext of Islamic windows.