Plato, Letters 319e

Συρακοσίοις καὶ Σικελιώταις πᾶσιν. ἀλλʼ ὦ τᾶν, εἰ μὲν μὴ φῂς εἰρηκέναι εἰρηκὼς ταῦτα, ἔχω τὴν δίκην· εἰ δʼ ὁμολογεῖς, τὸ μετὰ τοῦτο ἡγησάμενος εἶναι σοφὸν τὸν Στησίχορον, τὴν παλινῳδίαν αὐτοῦ μιμησάμενος, ἐκ τοῦ ψεύδους εἰς τὸν ἀληθῆ λόγον μεταστήσῃ.

if you deny having said this, when you have said it, I am justified; while if you confess it, you should further agree that Stesichorus was a wise man, and imitate his palinode, and renounce the false for the true tale.