On Jealousy and Envy.
Argument. — After Pointing Out that Jealousy or Envy is a Sin All the More Heinous in Proportion as Its Wickedness is Hidden, and that Its Origin is to Be Traced to the Devil, He Gives Illustrations of Envy from the Old Testament, and Gathers, by Reference to Special Vices, that Envy is the Root of All Wickedness. Therefore with Reason Was Fraternal Hatred Forbidden Not in One Place Only, But by Christ and His Apostles. Finally, Exhorting to the Love of One's Enemies by God's Example, He Dissuades from the Sin of Envy, by Urging the Rewards Set Before the Indulgence of Love.
Source: The Treatises of Cyprian (New Advent)