What is the ruling on eating the food of one who works in banks?

Question : Your Eminence the Shaykh! Some of our friends work in banks. Is it permissible for us to eat their food if they invite us?

Answer : Yes, it is permissible. It is permissible to eat their food and to advise them against working in banks. The Prophet (peace and blessings be upon him) ate from the food of the Jews. A Jewish woman offered him a sheep on the day of the conquest of Khaybar, and he ate from it. A Jew in Madinah invited him to barley bread and a thick soup, and he accepted. He also bought food from a Jew for his family, and the Prophet (peace and blessings be upon him) died before he paid the Jew, having pledged his armor to him. There is no harm in dealing with one who deals in what is forbidden by eating his food, accepting his gift, selling to him, and buying from him, but it is obligatory for you to advise him.