Are the funds a father takes from his son, knowing their illicit source, considered unlawful, and what sin is incurred by that?

If a father knows that the money he receives from his son is unlawful (haram), he is not permitted to accept it. Both the father and the son must repent to Allah and return the money to its rightful owners if possible. Otherwise, they should dispose of it by spending it on the poor. For a father to boast about a son who earns unlawful money and gives him some of it is a serious matter, as it indicates approval of evil and encourages it. It would have been more appropriate for the father to forbid and rebuke his son. Being keen on eating lawful (halal) earnings is one of the greatest acts of devotion. For one who consumes unlawful earnings, his prayer does not restrain him from indecency and evil, and he is in grave danger, as it is stated in the noble Hadith that consuming unlawful earnings prevents the acceptance of supplications.