Cyprian of Carthage, Three Books of Testimonies Against the Jews III.69: That we must depart from him who lives irregularly and contrary to discipline

Paul to the Thessalonians: “But we have commanded you, in the name of Jesus Christ, that ye depart from all brethren who walk disorderly, and not according to the tradition which they have received from us.” Also in the forty-ninth Psalm: “If thou sawest a thief, at once thou rannest with him, and placedst thy portion with the adulterers.”