Is it permissible to enter into a business partnership with someone who used to work at a usurious bank, and contributes money saved from his salary or end-of-service bonus from the usurious bank?

Working in an interest-based bank and receiving its salary is unlawful (haram). Therefore, it is impermissible to share with someone their sole money derived from this salary or their end-of-service gratuity from it, because it involves dealing with inherently unlawful money. However, if that person is poor and in need of the unlawful money, then it is permissible to share it with them in this case, because the money becomes permissible for them.