Passage 3.18.5
ἐμοὶ δὲ οὗτος ὁ Κναγεὺς ἄλλως ἀφικέσθαι πως ἐς Κρήτην φαίνεται καὶ οὐχ ὡς οἱ Λακεδαιμόνιοί φασιν, ἐπεὶ μηδὲ γενέσθαι δοκῶ πρὸς Ἀφίδνῃ μάχην Θησέως τε ἐν Θεσπρώτοις ἐχομένου καὶ Ἀθηναίων οὐχ ὁμονοούντων ἀλλὰ ἐς Μενεσθέα ῥεπόντων μᾶλλον ταῖς εὐνοίαις. οὐ μὴν οὐδὲ ἀγῶνος συμβάντος πείθοιτο ἄν τις αἰχμαλώτους ληφθῆναι παρὰ τῶν κρατησάντων, ἄλλως τε καὶ παρὰ πολὺ γενομένης τῆς νίκης, ὥστε ἁλῶναι καὶ αὐτὴν Ἄφιδναν.
But this man Knageus seems to me to have reached Crete in some other way, not as the Spartans claim. Indeed, I think that no battle took place at Aphidna, since Theseus was detained among the Thesprotians and the Athenians were not united, but rather leaning more toward Menestheus in their sympathies. Nor indeed would anyone be persuaded that captives were taken by the victors if no battle had even occurred, especially as the victory described was so decisive that Aphidna itself would have been captured.