What is the ruling on eating food from restaurants or accepting invitations to banquets if it is known that restaurants and cooks predominantly use nutmeg, which is prohibited, in their food?

The preponderant opinion is that nutmeg is impure, and its users must be reminded of its prohibition. Scholars and preachers should be urged to draw attention to this matter. If you know or strongly suspect that food contains it, do not consume it. Mere doubt, however, is not taken into consideration. It is advisable to cook your own food or have it cooked by someone you trust, or to eat foods that do not contain nutmeg, for wholesome food has blessed effects, including the answering of prayers. The narration concerning Umar ibn al-Khattab regarding the water trough does not indicate what you mentioned, and a group of scholars interpreted it as referring to the purity of the remnants left by predatory animals. Malik ibn Anas and those among the people of Hijaz who agreed with him saw no harm in the remnants of such animals.