Mixing with and accepting gifts from people dealing with usurious banks

Q 1: My father died and left us money and property. I have many siblings, and my elder brother is the one who runs all the properties and the factories. He deals in Riba (usury) with banks. One of our brothers is unsatisfied with this. He has tried hard to separate between his rights and those of his brothers, but he could not. He participates with his mother and siblings in consuming from the money mixed with Riba. What is the ruling on mixing with his siblings in eating and drinking?Some of his acquaintances also deal with usurious banks. What is the ruling on socializing with them, eating with them and accepting their presents?

(Part No. 14; Page No. 51) A: You should advise them and make it clear to them that dealing in Riba is Haram (prohibited) according to the Qur'an, the Sunnah and the Ijma` (consensus of scholars). As for eating with them, there is more than one case. You should not eat what you absolutely know to be gotten through unlawful ways; otherwise, you can eat from it. The ruling is the same on eating with your relatives and acquaintances. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.