Nicene and Post-Nicene Fathers, Vol. IV:
Writings in Connection with the Donatist Controversy.: Chapter 56

Chapter 56.—127.  Petilianus said:  "But even if, as you yourselves suppose, you are following the law of the Lord in purity, let us nevertheless consider the question of the most holy law itself in a legal form.  The Apostle Paul says, ‘The law is good, if a man use it lawfully.’ 2149   What then does the law say?  ‘Thou shalt not kill.’  What Cain the murderer did once, you have often done in slaying your brethren."

 128.  Augustin answered:  We do not wish p. 563 to be like you:  for there are not wanting words which might be uttered, as you too utter these; and known also, for you do not know these; and set forth in the conduct of a life, as these are not set forth by you.

Footnotes

1 Tim. i. 8.