Is it permissible to borrow from someone whose wealth is mixed with lawful and unlawful?

Question:
He says: Honorable Shaykh, may Allah grant you success. He says: I wanted to borrow a sum of money from one of the people, but his wealth is mixed with lawful and unlawful, and I was also informed that he does not pray, though I am not certain of that. Is it permissible for me to borrow from him?

Answer:
There is no harm in that, as long as you do not know that the money is forbidden. You borrow, sell, and buy. The Messenger (peace and blessings be upon him) used to eat from the food of the Jews and buy from them, and they dealt in riba (usury or interest), because not all of their wealth was riba; they had some lawful money. Yes.