Reference: al-Muntaqaa min Fataawa Fadheelatush-Shaykh Saalih Ibn Fowzaan – Volume 4, Page121, Fatwa No.123
Question: I am an employee at a bank, so is it permissible for me to perform Hajj from my earnings?
Response: Working in a bank which deals with ribaa is not permissible.
This is because it is assisting in sin and evil. And also, the Prophet (sal-Allaahu ‘alayhi wa sallam) cursed the one who ate/benefitted (aakil) from ribaa, as well as the one responsible [for the transactions], the witnesses [to the transactions] and the one who writes [the transactions].
Therefore, the employee in reality is assisting the bank, even if he is just a [bank] clerk. So he is cursed according to the text of the hadeeth. Based upon this, the wage he earns is haraam, and it is not permissible for him to eat/benefit from it and nor to perform Hajj with it. This is because the [performance of] Hajj requires pure/good earnings from halaal [sources], however, if he has [already] performed Hajj, then his Hajj is correct/sound but with sin [attached to it, i.e. lesser in reward].