Apophthegmata Laconica

Plutarch

Plutarch. Moralia, Vol. III. Babbitt, Frank Cole, translator. Cambridge, MA: Harvard University Press; London: William Heinemann Ltd., 1931 (printing).

When one of the Persians deserted from the king and was persuaded by Demaratus to change

his mind and return, and the king was going to have him put to death, Demaratus said, For shame, your Majesty! To think that when this man was your enemy you could not punish him for his desertion but now that he has become your friend, you would put him to death!