Muhaqqaq Masala

Breaking fast with something cooked by an unknown Muslim.

When a believer and Muslim brother is hosting an Iftar for us, we should assume, under the principle of "Thannu bil-Mu'minin Khayran" (think well of believers), that he is feeding us from halal wealth. Furthermore, we are bound by what is apparent, not the hidden (batin); therefore, we do not even have the right to investigate a Muslim. However, if it becomes known definitively through evidence and clues that he feeds people from haram wealth, then it is necessary to abstain from eating and drinking at such a person's place. (Kitab-un-Nawazil/Vol:6/Page:345)