Halakhah su Levitico 25:42

He prohibited - to not steal (kidnap) an Israelite person. And that is His saying in the Ten Commandments, "you shall not steal" (Exodus 20:13). And the language of the Mekhilta (Mekhilta d'Rabbi Yishmael 20:13:3) is, "'You shall not steal,' is the prohibition against stealing a soul." And in the Gemara, Sanhedrin (Sanhedrin 86a) they said, "From where [do we know] the prohibition against stealing souls? Rabbi Yoshiya says, 'From, "you shall not steal."' Rabbi Yochanan says, 'From, "They shall not be sold as slaves" (Leviticus 25:42).' And they do not disagree. One enumerates the prohibition against selling, etc." As they do not execute the punishment upon him until he steals (kidnaps) and sells. But once he transgressed these two negative commandments, he is liable for strangulation - as He, may He be exalted, said, "And one who steals a soul and sells him, etc." (Exodus 21:16). And the regulations of this commandment have already been explained in [Chapter] 1 of Sanhedrin. (See Parashat Yitro; Mishneh Torah, Theft 9.)

That we not sell a Hebrew slave upon the auctioning stone: - That we not sell a Hebrew slave in the way that we sell Canaanite (gentile) slaves, by announcement upon the auctioning stone, but rather discreetly and in an honorable fashion. And so did they say (Sifra, Behar, Section 6:1), "'They shall not be sold with the sale of a slave' (Leviticus 25:42) - that they not be sold in a market-stand and be placed up on the auctioning stone."