What is the legal ruling on working in the construction of banks and receiving wages or commissions for it?

If the questioner is building or selling materials to people who deal in usury to finance their activities, there is no blame on him, for the burden of the loan falls on the borrower. However, if he is working on building a property in which a usurious bank will conduct unlawful activities, then it is not permissible for him to work or sell for this building, because it involves assisting in sin.