Pausanias Description of Greece 2.13.8

[8]
  The Phliasians tell also the following legend. When Heracles came back safe from Libya , bringing the apples of the Hesperides, as they were called, he visited Phlius on some private matter. While he was staying there Oeneus came to him from Aetolia . He had already allied himself to the family of Heracles, and after his arrival on this occasion either he entertained Heracles or Heracles entertained him. Be this as it may, displeased with the drink given him Heracles struck on the head with one of his fingers the boy Cyathus, the cup-bearer of Oeneus, who died on the spot from the blow. A chapel keeps the memory of the deed fresh among the Phliasians; it is built by the side of the sanctuary of Apollo, and it contains statues made of stone representing Cyathus holding out a cup to Heracles.

[8] There is also a tale [ logos] told by Phliasians, and it goes like this. When Hēraklēs came back safe from Libya, bringing the apples of the Hesperides, as they were called, he visited Phleious on some private matter. While he was staying there Oineus came to him from Aetolia. He had already allied himself to the lineage of Hēraklēs, and after his arrival on this occasion either he entertained Hēraklēs or Hēraklēs entertained him. Be this as it may, displeased with the drink given him Hēraklēs struck on the head with one of his fingers the boy Cyathus, the cup-bearer of Oineus, who died on the spot from the blow. A chapel keeps the memory of the deed fresh among the Phliasians; it is built by the side of the sanctuary of Apollo, and it contains statues [ agalmata] made of stone representing Cyathus holding out a cup to Hēraklēs.