Diodorus Siculus Bibliotheca Historica 4.26.1:
Heracles, then, according to the myths which have come down to us, descended into the realm of Hades, and being welcomed like a brother by Persephonê brought Theseus and Peirithoüs back to the upper world after freeing them from their bonds. This he accomplished by the favour of Persephonê, and receiving the dog Cerberus in chains he carried him away to the amazement of all and exhibited him to men (original Greek).
Apollodorus Library 2.5.12:
A twelfth labour imposed on Hercules was to bring Cerberus from Hades. Now this Cerberus had three heads of dogs, the tail of a dragon, and on his back the heads of all sorts of snakes. When Hercules was about to depart to fetch him, he went to Eumolpus at Eleusis, wishing to be initiated. However it was not then lawful for foreigners to be initiated: since he proposed to be initiated as the adoptive son of Pylius. But not being able to see the mysteries because he had not been cleansed of the slaughter of the centaurs, he was cleansed by Eumolpus and then initiated. And having come to Taenarum in Laconia, where is the mouth of the descent to Hades, he descended through it. But when the souls saw him, they fled, save Meleager and the Gorgon Medusa. And Hercules drew his sword against the Gorgon, as if she were alive, but he learned from Hermes that she was an empty phantom. And being come near to the gates of Hades he found Theseus and Pirithous, him who wooed Persephone in wedlock and was therefore bound fast. And when they beheld Hercules, they stretched out their hands as if they should be raised from the dead by his might. And Theseus, indeed, he took by the hand and raised up, but when he would have brought up Pirithous, the earth quaked and he let go. And he rolled away also the stone of Ascalaphus. And wishing to provide the souls with blood, he slaughtered one of the kine of Hades. But Menoetes, son of Ceuthonymus, who tended the king, challenged Hercules to wrestle, and, being seized round the middle, had his ribs broken; howbeit, he was let off at the request of Persephone. When Hercules asked Pluto for Cerberus, Pluto ordered him to take the animal provided he mastered him without the use of the weapons which he carried. Hercules found him at the gates of Acheron, and, cased in his cuirass and covered by the lion’s skin, he flung his arms round the head of the brute, and though the dragon in its tail bit him, he never relaxed his grip and pressure till it yielded. So he carried it off and ascended throughTroezen. But Demeter turned Ascalaphus into a short-eared owl, and Hercules, after showing Cerberus to Eurystheus, carried him back to Hades (original Greek).
Hyginus Fabulae 79:
Theseus, son of Aegeus and Aethra, daughter of Pittheus, along with Pirithous, son of Ixion, carried off the maiden Helen, daughter of Tyndareus and Leda, from the shrine of Diana while she was sacrificing, and took her to Athens, to a district of the Attic region. When Jove saw that they had such audacity as to expose themselves to danger, he bade them in a dream both go and ask Pluto on Pirithous’ part for Proserpine in marriage. When they had descended to the Land of the Dead through the peninsula Taenarus, and had informed Pluto why they had come, they were stretched out and tortured for a long time by the Furies. When Hercules came to lead out the three-headed dog, they begged his promise of protection. He obtained the favour from Pluto, and brought them out unharmed. Castor and Pollux, Helen’s brothers, fought for her sake, and took Aethra, Theseus’ mother, and Phisadie, Pirithous’ sister, and gave them in servitude to their sister (original Latin).
Vergil Aeneid 6.610:
…or those who alone devoted themselves to riches obtained… (translated by Aaron J. Ivey)
Vergil Aeneid 6.617-618:
…he sits, and he will sit for an age: faithless Theseus… (translated by Aaron J. Ivey)
*Plutarch Theseus 31.4:
Then he himself, to return the service of Peirithous,journeyed with him to Epirus, in quest of the daughter of Aidoneus the king of the Molossians. This man called his wife Phersephone, his daughter Cora, and his dog Cerberus, with which beast he ordered that all suitors of his daughter should fight, promising her to him that should overcome it. However, when he learned that Peirithous and his friend were come not to woo, but to steal away his daughter, he seized them both. Peirithous he put out of the way at once by means of the dog, but Theseus he kept in close confinement (original Greek).
Plutarch Theseus 35.1:
Now while Heracles was the guest of Aidoneus the Molossian, the king incidentally spoke of the adventure of Theseus and Peirithous, telling what they had come there to do, and what they had suffered when they were found out. Heracles was greatly distressed by the inglorious death of the one, and by the impending death of the other. As for Peirithous, he thought it useless to complain, but he begged for the release of Theseus, and demanded that this favour be granted him (original Greek).
Edited by Aaron J. Ivey, Graduate Teaching Assistant, Department of Classics, University of Georgia, June 2016.