Iliad 9.312–313
Achilles to Odysseus during the embassy
ἐχθρὸς γάρ μοι κεῖνος ὁμῶς Ἀΐδαο πύλῃσιν
ὅς χʼ ἕτερον μὲν κεύθῃ ἐνὶ φρεσίν, ἄλλο δὲ εἴπῃ.
For as hateful to me as the gates of Hades is the man
who hides one thing within his heart and says another.