Plato, Laws 914a

δὲ τῆς ἄλλης χώρας, ἀγρονόμοις τε καὶ τοῖς τούτων ἄρχουσι δηλωσάτω. δηλωθέντων δέ, ἡ πόλις εἰς Δελφοὺς πεμπέτω· ὅτι δʼ ἂν ὁ θεὸς ἀναιρῇ περί τε τῶν χρημάτων καὶ τοῦ κινήσαντος, τοῦτο ἡ πόλις ὑπηρετοῦσα ταῖς μαντείαις δράτω τοῦ θεοῦ. καὶ ἐὰν μὲν ἐλεύθερος ὁ μηνύσας ᾖ, δόξαν ἀρετῆς κεκτήσθω, μὴ μηνύσας δέ, κακίας· δοῦλος δʼ ἐὰν ᾖ, μηνύσας μὲν ἐλεύθερος ὑπὸ τῆς πόλεως ὀρθῶς γίγνοιτʼ ἂν ἀποδιδούσης τῷ δεσπότῃ τὴν τιμήν, μὴ μηνύων δὲ θανάτῳ ζημιούσθω.

to the market-stewards; and if it occur in the country outside, he shall declare it to the rural stewards and their officers. And when such declarations are made, the State shall send to Delphi; and whatever the god pronounces concerning the goods and him that moved them, that the State shall execute, acting as agent on behalf of the oracles of the god. And if the informer be a free man, he shall win a reputation for virtue, but for vice if he fail to inform; and if he be a slave, as a reward for informing it will be right that he should be set free, by the State offering his price to his master, whereas he shall be punished by death if he fail to give information.