Pausanias Description of Greece 5.21.5

[5]
  Next after Eupolus they say that Callippus of Athens, who had entered for the pentathlum, bought off his fellow-competitors by bribes, and that this offence occurred at tie hundred and twelfth Festival. ¹ When the fine had been imposed by the Eleans on Callippus and his antagonists, the Athenians commissioned Hypereides to persuade the Eleans to remit them the fine. The Eleans refused this favour, and the Athenians were disdainful enough not to pay the money and to boycott the Olympic games, until finally the god at Delphi declared that he would deliver no oracle on any matter to the Athenians before they had paid the Eleans the fine.

[5] Next after Eupolos they say that Kallippos of Athens, who had entered for the pentathlon, bought off his fellow-competitors by bribes, and that this offence occurred at tie hundred and twelfth Festival. When the fine had been imposed by the Eleians on Kallippos and his antagonists, the Athenians commissioned Hypereides to persuade the Eleians to remit them the fine. The Eleians refused this favor, and the Athenians were disdainful enough not to pay the money and to boycott the Olympic Games, until finally the god at Delphi declared that he would deliver no oracle on any matter to the Athenians before they had paid the Eleians the fine.