Is it permissible to eat food offered by a friend who has embraced Islam, or to eat from what he buys, knowing that the source of his money is unlawful due to his father's work in gambling and selling pork?

Jurists have differed on the ruling concerning dealing with someone whose lawful wealth is mixed with unlawful wealth. The strongest of these are two opinions: - It is not forbidden to accept his gift or deal with him; rather, it is disliked. This is the adopted view of the Shafi'is and Hanbalis. - One should look at the predominant nature of the wealth. If lawful wealth predominates, then it is permissible to deal with him. If unlawful wealth predominates, then it is not permissible. This is the doctrine of the Hanafis and Malikis.

The more accurate view is the permissibility of dealing with him and accepting his gift. This is indicated by the fact that the Prophet, peace and blessings be upon him, accepted the gift of the Jewish woman and ate from the food of the Jew, and he dealt with him in buying and selling, even though the Jews are "listeners to falsehood, devourers of unlawful gain."

Therefore, there is no harm in accepting the gift and eating from your friend's food, unless your refusal would affect him and lead him to repentance.