History of the Peloponnesian War

Now Astyochus did not so much as think of punishing Alcibiades—especially as he no longer put himself in his power as he used to do—but having gone up to him and Tissaphernes at Magnesia, at once told them the contents of the letter from Samos, acting as an informer to them, and for his own private gain devoting himself, as was said, to the interest of Tissaphernes both on these and on all other matters:

for which reason also he was the more gentle in remonstrating with him respecting the pay not being given in full.

Alcibiades immediately sent a letter to Samos giving information against Phrynichus to the authorities there, telling them what he had done, and requiring that he should be put to death. Phrynichus, being confounded and in the most extreme danger, sent again to Astyochus, reproaching him because his former information had not been duly kept secret, and telling him now that he was prepared to give them an opportunity of destroying the whole Athenian armament at Samos; describing the particulars of the way in which he could do it, as Samos was unfortified; and pleading that it was not now culpable in him, being, as he was, in danger of his life through them, to do this, or any thing else, rather than be destroyed by his bitterest enemies. Astyochus gave information of this also to Alcibiades.