Plato, Laws 916c

δὲ ἰδιώτῃ τις ἰδιώτης, ἀναγωγὴν μὲν εἶναι, καθάπερ καὶ τοῖς πρόσθεν ἐρρήθη, καὶ τὴν διαδικασίαν, ὁ δὲ ὀφλὼν τὴν τιμὴν ἁπλῆν ἀποτινέτω. ἐὰν δὲ ἀνδροφόνον ἀποδῶταί τίς τινι εἰδότι μὲν εἰδώς, μὴ τυγχανέτω ἀναγωγῆς τοῦ τοιούτου τῆς πράσεως, μὴ δὲ εἰδότι τὴν μὲν ἀναγωγὴν εἶναι τότε ὅταν τις αἴσθηται τῶν πριαμένων, ἐν πέντε δὲ τῶν νομοφυλάκων τοῖς νεωτάτοις εἶναι τὴν κρίσιν, εἰδὼς δὲ ἂν κριθῇ, τάς τε οἰκίας τοῦ πριαμένου καθηράτω κατὰ τὸν τῶν ἐξηγητῶν

If a lay person sells to a lay person, there shall be the same right of restitution and trial as in the cases just mentioned; but the losing party shall pay the selling price only. If a man wittingly sells a murderer, if the buyer is aware of the fact, he shall have no claim to restitution for the purchase of such an one; but if the buyer be ignorant, he shall have right of restitution as soon as the fact is perceived, and the trial shall take place before a court of the five youngest Law-wardens, and if it be decided that the seller acted wittingly, he shall purify the houses of the buyer as ordained by the interpreters, and he shall pay three times the selling price to the buyer.