All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
We hope that there is nothing wrong with you eating from his money, especially if it is mixed, some of it is lawful and some of it is ill-gotten.
Some scholars said that the money which is forbidden because of the way it was earned and is not forbidden in itself; this money is only forbidden to be used by the one who earned it.
Shaykh Ibn 'Uthaymeen was asked:
A man knows that the source of his father's wealth is forbidden; can he eat his father’s food? If he does not eat his father's food, is that considered undutifulness to his father?
“With regard to the man who knows that his father's wealth is forbidden, if it is forbidden in and of itself, like if he knows that his father stole this money from someone for example, then it is not permissible for him to eat it. Nevertheless, if it is forbidden because of the way in which it was earned, such as if he (the father) deals with Riba or cheats and so on, then (he can) eat, and the sin is on him (the father).
The evidence for this is that the Prophet ate from the money of the Jews, who are known to deal in Riba and consume what is forbidden. Also, a Jewish woman gifted him a poisoned sheep in Khaybar so that he would die, but Allah protected him against that until an appointed time. Moreover, a Jewish man invited him to eat barley bread and fat, and he accepted his invitation and ate. He also bought food for his family from a Jew, and he and his family ate from it. So let him [the man asking the question] eat and the sin is on his father.” [End of quote]
Allah knows best.