Maalik ibn Anas (radhi-yallaahu 'anhu) said:

((Whoever does not love knowledge, then there is no good in him; So there should not be any acquaintence between you and him, and nor any friendship)).

al-Khateeb in al-Faqeeh wal-Mutafaqqih - Volume 1, Page 15;

Mabaahith fee Ahkaam al-Fatwa - Page 12

Ref: Fatwa-Online

Shaykhul Islaam Taqee ad-Deen ibn Taymiyyah said:

"If the source of this person’s wealth is not known then it is not forbidden to eat [take] from him. However, if it is known that this person’s wealth has been…"

Ref: Eating from lawful and unlawful sources