Sanhedrin 59b. Quoted in Abraham Isaac Kook, "Fragments of Light: A View as to the Reasons for the Commandments," in The Lights of Penitence, The Moral Principles, Lights of Holiness, Essays, Letters, and Poems, trans. Ben Zion Bokser (New York: Paulist Press, 1978), p. 317.https://en.wikiquote.org/wiki/Jewish_vegetarianism