The Jewish authorities appear to be right in referring this law, like those in Exodus 21:26-27, Exodus 21:32, to foreign slaves (see Leviticus 25:44-46). The protection here afforded to the life of a slave may seem to us but a slight one; but it is the very earliest trace of such protection in legislation, and it stands in strong and favorable contrast with the old laws of Greece, Rome, and other nations. If the slave survived the castigation a day or two, the master did not become amenable to the law, because the loss of the slave was accounted, under the circumstances, as a punishment.
Related Commentaries of Exodus 21:20
Exodus 21:20-21
20 And if a man smite his servant, or his maid, with a rod, and he die under his hand; he shall be surely punished.e
21 Notwithstanding, if he continue a day or two, he shall not be punished: for he is his money.