The World Federation One Stop Fiqh

Ruling 139

If the owner of a house finds out during a meal that the food is impure, he must tell the guests about it provided that the second condition mentioned [in Ruling 136] is fulfilled. However, if one of the guests finds out, it is not necessary for him to tell the others about it. Furthermore, in the event that his dealings with the other guests are such that if they became impure he would also become impure and this would result in him doing something that was contrary to an obligatory religious ruling, he must tell them.