Who dares think one thing, and another tell,
My heart detests him as the gates of hell.

[Ἐχθρὸς γάρ μοι κεῖνος ὁμῶς Ἀΐδαο πύλῃσιν
ὅς χ’ ἕτερον μὲν κεύθῃ ἐνὶ φρεσίν, ἄλλο δὲ εἴπῃ.]

Homer (fl. 7th-8th C. BC) Greek author

The Iliad [Ἰλιάς], Book 9, l. 312ff (9.312-313) [Achilles to Odysseus] (c. 750 BC) [tr. Pope (1715-20)]
    (Source)

Original Greek. Alt. trans.:

For, like hell mouth I loath, Who holds not in his words and thoughts one indistinguish’d troth. [tr. Chapman (1611), ll. 300-01]

For I abhor the man, not more the gates Of hell itself, whose words belie his heart. [tr. Cowper (1791), ll. 385-86]

Hateful to me as the gates of Hades is he who conceals one thing in his mind and utters another. [tr. Buckley (1860)]

Him as the gates of hell my soul abhors,
Whose outward words his inmost thoughts conceal.
[tr. Derby (1864), ll. 373-74]

For hateful to me even as the gates of hell is he that hideth one thing in his heart and uttereth another. [tr. Leaf/Lang/Myers (1891)]

Him do I hate even as the gates of hell who says one thing while he hides another in his heart.
[tr. Butler (1898)]

I hate
as I hate Hell's own gate that man who hides
one thought within him while he speaks another.
[tr. Fitzgerald (1974), l. 381ff]

I hate that man like the very Gates of Death
who says one thing but hides another in his heart.
[tr. Fagles (1990), ll. 378-79]