Praise be to Allaah.
You should not borrow from this person or have any dealings with him so long as he is dealing in haraam things or is known for haraam dealings, whether that is riba or anything else. You should not deal with him or borrow from him, rather you should avoid that and keep away from it.
But if he deals with haraam things and non-haraam things, i.e., his dealings are a combination of good and bad, then there is nothing wrong with it, but it is better not to do that, because the Prophet (peace and blessings of Allaah be upon him) said: “Leave that which makes you doubt for that which does not make you doubt.” Narrated by al-Tirmidhi. 2518; classed as saheeh by al-Albaani in Saheeh al-Tirmidhi. And he (peace and blessings of Allaah be upon him) said: “Whoever avoids doubtful matters will protect his religious commitment and his honour.” Agreed upon. And he (peace and blessings of Allaah be upon him) said: “Sin is that which wavers in your heart and you dislike the people finding out about.” Narrated by al-Tirmidhi, 2389; classed as saheeh by al-Albaani in Saheeh al-Tirmidhi.
So the believer should keep away from doubtful matters. If you know that all his dealings are haraam and that he trades in haraam things, then you should not deal with such a person or borrow from him. End quote.
Majmoo’ Fataawa Ibn Baaz, 19/286.