Diodorus Siculus 4.73
Now that we have examined these matters we shall endeavor to set forth the facts concerning Pelops and Tantalus and Oenomaüs, but to do so we must revert to earlier times and give in summary the whole story from the beginning. The account runs like this: In the city of Pisa in the Peloponnesus Ares lay with Harpinê, the daughter of Asopus, 2 and begat Oenomaüs, who, in turn, begat a daughter, an only child, and named her Hippodameia. And once when he consulted an oracle about the end of his life the god replied to him that he should die whenever his daughter Hippodameia should marry. Consequently, we are told, he proceeded cautiously regarding the marriage of his daughter and decided to see that she was kept a virgin, assuming that only in this way could he escape from the danger which her marriage would entail. 3 And so, since there were many suitors for the girl's hand, he proposed a contest for any who wished of the marry her, the conditions being that the defeated suitor must die, but whoever should win would have the girl in marriage. The contest he set was a chariot-race from Pisa to the altar of Poseidon on the Isthmus of Corinth,and the starting of the horses he arranged as follows: 4 Oenomaüs was to be sacrificing a ram to Zeus, when the suitor should set out, driving a chariot drawn by four horses; then, when the sacrifice had been completed, Oenomaüs was to begin the race and make after the suitor, having a spear and Myrtilus as his driver, and if he should succeed in overtaking the chariot which he was pursuing he was to smite the suitor with the spear and slay him. By employing this method he kept overtaking the suitors as they appeared, his horses being swift, and was slaying them in great numbers. 5 But when Pelops, the son of Tantalus, came to Pisa and looked upon Hippodameia, he set his heart upon marrying her, and by corrupting Myrtilus, the charioteer of Oenomaüs, and thus securing his co-operation toward winning the victory, he was the first to arrive at the altar of Poseidon on the Isthmus. 6 And Oenomaüs, believing that the oracle had been fulfilled, was so disheartened by grief that he removed himself from life. In this way, then, Pelops got Hippodameia for his wife and succeeded to the sovereignty of Pisa, and increasing steadily in power by reason of his courage and his wisdom, he won over to himself the larger number of those who dwelt in the Peloponnesus and called the land after his own name "Peloponnesus."