Polycarp's Zinger

For more than half a century Polycarp devoted himself to teaching sound doctrine and opposing heresy. Once on a visit to rome he had snubbed the heretic Marcion. "Don't you know who I am, Polycarp?" he asked. "Oh yes," said the saint, "I know the firstborn of Satan when I see him."

Bert Ghezzi, The Voices of the Saints

I wish I was that quick with a witty quip.