Chapter 76.
167 Petilianus said: "But to us the Lord Christ, in opposition to your deadly commands, commanded simple patience and harmlessness. For what says He? ‘A new commandment I give unto you, That ye love one another; as I have loved you, that you also love one another.' And again, ‘By this shall all men know that you are my disciples, if you have love one to another.'"
168. Augustine answered: If you did not transfer these words, so widely differing from your character, to the surface of your talk, how could you be covering yourselves with sheep's clothing?
Source: Answer to Letters of Petilian, Bishop of Cirta (New Advent)