Mishnayos Eruchin Perek 3 Mishnah 3

There are halakhot with regard to a forewarned ox that killed a Canaanite slave that are lenient and others that are stringent; how so? Both in the case of an ox that killed the most attractive among the slaves, whose value is great, and likewise in the case of one that killed the most unsightly among the slaves, whose value is minimal, its owner gives payment of thirty sela, the fine stated in the Torah (Exodus 21:32), to the owner of the slave. If the ox killed a freeman, its owner gives his price as payment to his heirs. This sum can be more or less than thirty shekels. If the ox injured this slave or that freeman, he gives payment of the full cost of the damage as compensation.

בְּשׁוֹר הַמּוּעָד שֶׁהֵמִית אֶת הָעֶבֶד לְהָקֵל וּלְהַחֲמִיר. כֵּיצַד. אֶחָד שֶׁהֵמִית אֶת הַנָּאֶה שֶׁבָּעֲבָדִים וְאֶת הַכָּעוּר שֶׁבָּעֲבָדִים, נוֹתֵן שְׁלשִׁים סֶלַע. הֵמִית בֶּן חוֹרִין, נוֹתֵן אֶת שָׁוְיוֹ. חָבַל בָּזֶה וּבָזֶה, מְשַׁלֵּם נֶזֶק שָׁלֵם: