The ruling on dealing with an institution that deals in riba (usury or interest)

Question:
And I move on to this question. He says: Is it permissible for me to deal with an institution that deals with riba (usury or interest) banks, while my contract with the institution is free from riba?

Answer:
If the institution has permissible transactions and forbidden transactions, there is no harm in dealing with it in the permissible transactions, provided you do not enter into the forbidden transactions with it. The Prophet (peace and blessings be upon him) dealt with the Jews; he bought from them and ate their food, and they were dealing in riba, but not all of their wealth was from riba.