Plato, Laws 865c

ἑαυτοῦ σώματι ἢ διʼ ἑτέρων σωμάτων, πάντως ἔστω μὲν ὡς αὐτόχειρ, δίκας δὲ τινέτω τὰς τοιάσδε· ἐὰν μὲν δοῦλον κτείνῃ, νομίζων τὸν ἑαυτοῦ διειργάσθαι τὸν τοῦ τελευτήσαντος δεσπότην ἀβλαβῆ παρεχέτω καὶ ἀζήμιον, ἢ δίκην εἰς τὴν ἀξίαν τοῦ τελευτήσαντος ὑπεχέτω διπλῆν, τῆς δὲ ἀξίας οἱ δικασταὶ διάγνωσιν ποιείσθωσαν, καθαρμοῖς δὲ χρήσασθαι μείζοσίν τε καὶ πλείοσι τῶν περὶ τὰ ἆθλα ἀποκτεινάντων,

in all cases it shall be accounted to be his own personal act, and he shall pay the following penalties. If he kill a slave, he shall secure the master against damage and loss, reckoning as if it were a slave of his own that had been destroyed, or else he shall be liable to a penalty of double the value of the dead man,—and the judges shall make an assessment of his value,—and he must also employ means of purification greater and more numerous than those employed by persons