brother if a person is building houses as his job using halal money and sells them to people who are buying them in ribaa, does this person fall into sin. because living in the west it is common knowledge that most people get a loan to buy homes and cannot really afford to buy them cash.
Praise be to Allaah.
It is better not to get involved with these kinds of transactions, in order to be on the safe side, but the basic principle is that he has nothing to do with the riba-based transaction and he is not a party to it, because the party which is consuming riba is the bank and the one who is paying it is the purchaser of the house.
Shaykh Ibn Jibreen