Say, "Have you seen what God has sent down to you from provisions, then you made some of it forbidden and some lawful?" Say, "Did God authorize you, or did you invent lies against God?"
Translation endnotes
[10:59-60] Attributing to God man-made prohibitions is considered polytheism, idolatry. According to the Quran, the religious leaders and clerics who commit this crime are the worst enemies of God. For instance, recently, Iranian mullahs prohibited fish with no scales. Some Turkish clerics prohibit lobster, mussel, crab, shrimp and many other excellent sources of nutrition; they attribute their prohibitions to God. See 6:145-155.