Is it permissible to borrow money from someone whose wealth is unlawful, given a very urgent need for money for the purpose of marriage, and with the intention of repaying the loan properly?

It is permissible to borrow from someone whose money is mixed (some lawful and some unlawful), unless it is known that the borrowed money itself is unlawful. However, if a person's entire wealth is unlawful, then it is not permissible to borrow from him.