Is the slaughter of a People of the Book (Ahl al-Kitab) permissible, regardless of their status as enemy combatants (Harbi) or protected subjects (Dhimmi)?

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The slaughter of a People of the Book is permissible, whether they are enemy combatants or protected subjects. The slaughter of those who are not People of the Book is forbidden. Imam Ahmad permitted the slaughter of the People of the Book who are at war, citing the narration of Abdullah ibn Mughaffal regarding fat (shaham). Ishaq agreed with this view. Ibn al-Mundhir reported consensus on this ruling among the scholars whose opinions are known, including Mujahid, Al-Thawri, Al-Shafi'i, Ahmad, Ishaq, Abu Thawr, and the Companions of the School of Thought (Ahl al-Ra'y). The evidence is general in scope concerning them.