"Caedite eos. Novit enim Dominus qui sunt eius." is a Latin phrase reportedly spoken by the commander of the Albigensian Crusade, prior to the massacre at Béziers on 22 July 1209. A direct translation
Pope Innocent III (enthroned) and Arnold of Citeaux, kneeling
Innocent III excommunicating the Albigensians, left, and their massacre by the crusaders, right