History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
So much they said in regard to their ancient oaths, but as to the Argive alliance they would consult with their friends and do whatever was right. So the envoys of the Lacedaemonians returned home. But there happened to be at Corinth Argive envoys, who urged the Corinthians to come into the alliance without delay; the latter, however, told them to come to their next assembly.
Soon after there also came an embassy of the Eleans and first concluded an alliance with the Corinthians, and then they proceeded to Argos, as they had been instructed, and made an alliance with the Argives. It seems that at one time the Eleans were at variance with the Lacedaemonians about Lepreum.[*](In Triphylia, not far from the boundaries of Elis and Laconia (5.34.1).)
For when there had been a war between the Lepreates and some of the Arcadians, and the Eleans had been invited by the Lepreates to make an alliance with them, with the offer of half their territory, on the conclusion of the war the Eleans left the Lepreates in possession of their land, but assessed upon them a tax of a talent to be paid to Olympian Zeus.
Now up to the war with Athens they regularly paid the tribute; then on the pretext of the war they ceased to pay the tribute, and the Eleans tried to enforce payment, whereupon they had recourse to the Lacedaemonians. The case having been referred to the Lacedaemonians for arbitration, the Eleans, suspecting that they would not receive fair treatment, renounced the arbitration and ravaged the land of the Lepreates.