Sefer HaChinuch ספר החינוך

The commandment of the law of a Hebrew slave: To adjudicate the law of a Hebrew slave according to what is written in the section, as it is stated (Exodus 21:2), “When you acquire a Hebrew slave, etc.” [This] means to say that we do the things to him that we are commanded about: For example, to send him away in the seventh year (Kiddushin 14b), or within the six years if the Jubilee occurs [before the end of his term], or by subtracting [with] money, or with the death of a master who did not leave a male child. And [we] also [do] for the “pierced one,” according to the laws that are written about him. Everything is like our Rabbis, may their memory be blessed, taught us from the verse, as it is explained in the first chapter of Kiddushin 14b.

It is from the roots of this commandment that God wanted His people Israel that He chose, to be a holy nation, full of — and crowned with — good and lofty traits; as blessing rests upon them from this. And kindness and mercy are from the most praiseworthy traits in the world. And therefore, He warned us to have mercy on the one under our hand and to do kindness towards him, as is written in the section, and as we know also from the tradition (Sifra, Behar).

The laws of the commandment — for example, the differences between one who sells himself and one who is sold by the court; the things for which he is sold and those for which he goes free; and the rest of its laws — are [all] elucidated there in Kiddushin. (See Tur, Yoreh Deah 263.)

And the commandment is practiced by males, but not by females — as a woman does not acquire a Hebrew slave (Bava Metzia 71a). And [this is] specifically when Israel is dwelling on its land — as so does the received explanation (Arakhin 29a) come [to tell us], that [the law of] a Hebrew slave is only practiced when the Jubilee is practiced. And it is explicit (Arakhin 32b) that the law of Jubilee is only in the Land. And one who transgresses it and does not do to the slave that which is written about him, negates a positive commandment, and also teaches his soul to be cruel. And it is almost as if he testifies about himself that he is not from the Children of Israel, since they are merciful ones [who are] the children of merciful ones (Shabbat 97a; Yevamot 79a).