Plato, Letters 335a

ἐστιν τοῖς ἀψύχοις, ἀλλʼ ἢ μετὰ σώματος οὔσῃ ψυχῇ τοῦτο συμβήσεται ἑκάστῃ ἢ κεχωρισμένῃ. πείθεσθαι δὲ ὄντως ἀεὶ χρὴ τοῖς παλαιοῖς τε καὶ ἱεροῖς λόγοις, οἳ δὴ μηνύουσιν ἡμῖν ἀθάνατον ψυχὴν εἶναι δικαστάς τε ἴσχειν καὶ τίνειν τὰς μεγίστας τιμωρίας, ὅταν τις ἀπαλλαχθῇ τοῦ σώματος· διὸ καὶ τὰ μεγάλα ἁμαρτήματα καὶ ἀδικήματα σμικρότερον εἶναι χρὴ νομίζειν κακὸν πάσχειν ἢ δρᾶσαι, ὧν ὁ φιλοχρήματος

belongs to what is soulless, but they befall the soul whether it be united with a body or separated therefrom. But we ought always truly to believe the ancient and holy doctrines which declare to us that the soul is immortal and that it has judges and pays the greatest penalties, whensoever a man is released from his body; wherefore also one should account it a lesser evil to suffer than to perform the great iniquities and injustices. But to these doctrines the man who is fond of riches but poor