“Do not let your deeds belie your words, lest when you speak in church someone may say to himself, "Why do you not practice what you preach?"”
Non confundant opera tua sermonem tuum: ne cum in Ecclesia loqueris, tacitus quilibet respondeat, cur ergo haec quae dicis, ipse non facis?
Jerome (345–420) Catholic saint and Doctor of the Church
Letter 52
Letters