History of the Peloponnesian War
Thucydides
Thucydides. History of the Peloponnesian War. Crawley, Richard, translator. London and Toronto: J. M. Dent and Sons Ltd.; New York: E. P. Dutton and Co., 1914.
4. As to the offering to the god, the Argives, if they wish, shall impose an oath upon the Epidaurians, but, if not, they shall swear it themselves.