Torah Portion: Mishpatim
When you buy a Hebrew slave, he shall serve for six years, but in the seventh year, he is to be set free without liability (Shemos 21:2).
It is a positive commandment to carry out the law of a Hebrew slave as described in the portion [of the Torah that discuses Hebrew slaves], for it says: When you buy a Hebrew slave etc. (Shemos 21:2). That is to say, we should do for him all the things about which we were commanded; this includes, for instance: to send him free in the seventh year of his servitude or within the six years of servitude if the Yovel year occurred during the period, or by redeeming himself with money, or through the death of the owner who did not leave an inheriting son. The mitzvah also includes to treat the slave-with-the bored-earlobe (eved nirtza) in accord with the law written about such cases.
Among the roots of this mitzvah is the idea that God wished His people Israel, whom He chose, to be a holy people filled and adorned with every good and noble quality; for as a result, blessing will be bestowed upon them. And since kindness and mercy are among the most worthy qualities in the world, He therefore warned us to have mercy on someone who is under our ownership, and to treat him with kindness.
This mitzvah applies to men but not to women—for a woman may not buy a Hebrew slave—and only when the Yovel cycle is in effect and then only in the land of Eretz Yisrael. One who transgressed this and did not treat a slave as it is written concerning him, violated a positive commandment and has also taught himself to be a cruel person. He is virtually attesting about himself that he is not a Jew, for they are compassionate people, sons of compassionate [ancestors].