Then, do not have one mind, and one alone
that only your opinion can be right.
Whoever thinks that he alone is wise,
his eloquence, his mind, above the rest,
come the unfolding, shows his emptiness.

[μή νυν ἓν ἦθος μοῦνον ἐν σαυτῷ φόρει,
ὡς φὴς σύ, κοὐδὲν ἄλλο, τοῦτ᾽ ὀρθῶς ἔχειν.
ὅστις γὰρ αὐτὸς ἢ φρονεῖν μόνος δοκεῖ,
ἢ γλῶσσαν, ἣν οὐκ ἄλλος, ἢ ψυχὴν ἔχειν,
οὗτοι διαπτυχθέντες ὤφθησαν κενοί.]

Sophocles (496-406 BC) Greek tragic playwright
Antigone, ll. 705-709 ff [Haemon] (441 BC) [tr. Wyckoff]
    (Source)

Original Greek. Alt. trans.:

Then cleave not solely to this principle --
Thy words, no other man's, are free from error.
For whoso thinks that he alone is wise,
That his discourse and reason are unmatched,
He, when unwrapt, displays his emptiness.
[tr. Donaldson (1848)]

Therefore, my father, cling not to one mood,
And deem not thou art right, all others wrong.
For whoso thinks that wisdom dwells with him,
That he alone can speak or think aright,
Such oracles are empty breath when tried.
[tr. Storr (1859)]

Do not, then, bear one mood only in yourself: do not think that your word and no other, must be right. For if any man thinks that he alone is wise -- that in speech or in mind he has no peer -- such a soul, when laid open, is always found empty.
[tr. Jebb (1891)]

Oh, do not, then, retain thy will
And still believe no sense but thine
Can judge aright; the man who proudly thinks
None but himself or eloquent or wise,
By time betrayed is branded for an idiot.
[tr. Werner (1892)]

Wear not, then, one mood only in thyself; think not that thy word, and thine alone, must be right. For if any man thinks that he alone is wise, -- that in speech, or in mind, he hath no peer, -- such a soul, when laid open, is ever found empty.
[tr. Jebb (1917)]

I beg you, do not be unchangeable:
Do not believe that you alone can be right.
The man who thinks that,
The man who maintains that only he has the power
To reason correctly, the gift to speak, to soul ––
A man like that, when you know him, turns out empty.
[tr. Fitts/Fitzgerald (1939), ll. 564 ff]

Therefore I say,
Let not your first thought be your only thought.
Think if there cannot be some other way.
Surely, to think your own the only wisdom,
And yours the only word, the only will,
Betrays a shallow spirit, an empty heart.
[tr. Watling (1947), ll. 602 ff]

And now, don't always cling to the same anger,
Don't keep saying that this, and nothing else, is right.
If a man believes that he along has a sound mind,
And no one else can speak or think as well as he does,
Then, when people study him, they'll find an empty book.
[tr. Woodruff (2001)]

So, don’t be so single-minded. You said it yourself quite rightly: he who thinks that he’s the only one with a brain or a tongue or a soul, if you open him up you’ll find that he’s a hollow man.
[tr. Theodoridis (2004)]

So don’t let your mind dwell on just one thought,
that what you say is right and nothing else.
A man who thinks that only he is wise,
that he can speak and think like no one else,
when such men are exposed, then all can see
their emptiness inside.
[tr. Johnston (2005), ll. 799 ff]

Do not wear one and only one frame of mind in yourself,
that what you say, and nothing else, is right.
Whoever imagines that he and he alone has sense
or has a tongue or an essence that no other has,
these men, when unfolded, are seen to be empty.
[tr. Tyrell/Bennett]