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.
adopted city.[*](Possibly τὴν ἐκείνου πόλιν τὸ μέρος means a city in a measure his own.)To this Sadocus agreed, and sending some troops to accompany Learchus and Ameiniades, seized them as they journeyed through Thrace before they embarked on the boat by which they were to cross the Hellespont. They were then, in accordance with his orders, delivered to the Athenian envoys, who took them and brought them
to Athens. When they arrived, the Athenians, in fear that Aristeus might escape and do them still more harm, because he had evidently been the prime mover in all the earlier intrigues at Potidaea and along the coast of Thrace, put them all to death on that very day without a trial, though they wished to say something in their own defence, and threw their bodies into a pit, thinking it justifiable to employ for their own protection the same measures as had in the first instance been used by the Lacedaemonians when they killed and cast into pits the traders of the Athenians and their allies whom they caught on board merchantmen on the coast of the Peloponnesus. For at the beginning of the war all persons whom the Lacedaemonians captured at sea they destroyed as enemies, whether they were fighting on the side of the Athenians or not even taking part on either side.