Exodus 21:20

And when a man hath smitten his Kenaanite man-servant or maid-servant with a staff, and he die the same day under his hand, he shall be judged with the judgment of death by the sword.

IF A MAN SMITE HIS BONDMAN. Our Sages have already perforce derived from the expression, for he is his money, that this verse speaks of a Canaanite bondman, and the plain meaning of Scripture is indeed as they say, for his countryman, a Hebrew man or woman, is not called plain eved or amah without any further qualifications. Scripture states ‘basheivet’ [with a patach under the beth, which indicates the definite article, thus meaning] “with the rod”: [And if a man smite his bondman, or his bondwoman, with the rod], because it is the custom of a ruler or master to keep in his hand a rod, and G-d therefore warned him that even if it be a rod of correction and not a wooden cane, he should be careful with it and should not use it to hit even a Ganaanite bondman with a persecution that none restrained. This is the purport of the expression, and he die under his hand, meaning that he kept striking him until he died. It was not necessary for Scripture to state the punishment which he is liable to, but it just stated that he is not to go free merely because the bondman is his money, but he shall surely be punished, as is the punishment of anyone who strikes another person so that he dies, where Scripture has said, he shall surely be put to death.
In line with the plain meaning of Scripture the intention of: Notwithstanding, if a day or two ‘ya’amod’, [generally translated “he continues”], is that the bondman literally gets up “and stands” on his feet. This is why it was necessary for Scripture to say a day or two, the meaning thereof being that if on that day or on the following day the bondman will stand up on his feet, he [i.e., the master] shall not be punished. And the verse is to be understood as if it said: “notwithstanding, [if he stands up] ‘bayom’ or ‘bayomayim’ (in a day or in two) or ‘l’yom’ or ‘l’yomayim’ (to a day or to two). [literally: “a day or two”]. This fits in with the translation of ya’amod as “he continues,” thus: if he continues [living] a day or two. Ramban who interprets ya’amod in its literal sense — “he stands up” — therefore concludes that the sense of the verse is: “notwithstanding, if he stands up in a day or in two etc.” The opinion of the Rabbis mentioned further on will explain sufficiently why the Torah did write here …

בשבט, an example of an instrument used to administer physical punishment to one’s slave in order to discipline him. If the slave had been struck with a sword, for instance, even if he had not died within the first twenty four hours, the master would be guilty of manslaughter as the tool used to inflict the injury points at criminal rather than disciplinary intention. The subject of our verse is a gentile slave. A Jewish servant, by contrast, not being the personal property of his master, is treated legally in all respects as if he were a hired hand, with the exception of his master (employer’s ) right to give him a gentile slave as his wife.

נקום ינקם, the blood of the slave. The master is certainly not permitted to administer such a cruel blow even though he owns this human being. He is allowed to administer physical punishments as we know from Proverbs 29,19 בדברים לא יוסר עבד, “a slave does not respond to mere oral chastisement.”