‘This sheep tells me that it contains poison.’” Had the animals they slaughtered not been lawful to eat, he would not have eaten any of that sheep.

It is also established in an authentic hadith:

“When they went on the expedition to Khaybar, one of the Companions took a leather bag containing fat. He said, ‘I said, “I will not share any of this with anyone today.” Then I turned around, and there was the Messenger of Allah, may Allah bless him and grant him peace, laughing.’ He did not rebuke him.”

Scholars have cited this as evidence that the Muslim army may eat the food of those at war with them before the spoils are divided.

Furthermore:

“The Messenger of Allah, may Allah bless him and grant him peace, accepted a Jew’s invitation to a meal of barley bread and rancid rendered fat.”

This was narrated by Imam Ahmad. Ihālah (rendered fat) is fat obtained from a slaughtered animal, such as clarified butter and the like, which is ordinarily found in their cooking vessels. Had the animals they slaughtered been forbidden to eat, their vessels would have been like those of the Magians and others like them. It is established that the Prophet, may Allah bless him and grant him peace,

“forbade eating from their vessels, then permitted it provided they were washed.”

Moreover, it is widely reported that when the Companions of the Messenger of Allah, may Allah bless him and grant him peace, conquered Syria, Iraq, and Egypt, they ate animals slaughtered by the People of the Book—Jews and Christians—and abstained only from those slaughtered by the Magians.

The cheese made by the Magians gave rise to the well-known disagreement among Muslims, because cheese requires rennet, and scholars have a well-known disagreement concerning rennet from an animal that has not been lawfully slaughtered. Abū Hanīfah holds that it is ritually pure, whereas Mālik and al-Shāfiʿī hold that it is ritually impure. Two opinions are reported from Ahmad.