Midrasz do Kapłańska 25:46

(Ibid.) "If you buy (lit.,) a servant Hebrew": Is Scripture speaking of a servant who is a Hebrew, or the servant of a Hebrew? And how am I to understand (Leviticus 25:46) "And you shall hold them as an inheritance for your sons after you, etc."? As referring to (a gentile servant) bought from a gentile; but if he were bought from a Jew, (I would say that) he serves six years and goes free on the seventh. It is, therefore, written (Devarim 15:12) "If there be sold to you (by beth-din for his theft) your brother, the Hebrew man or the Hebrew woman, etc." Let it not be written "Hebrew man" or "Hebrew woman," for it is already written "your brother." Why is it written? It is deliberately superfluous to signal a gezeirah shavah (i.e., "identity"), viz.: It is written here (in Exodus) "Hebrew," and there (in Devarim) "Hebrew." Just as there, "Hebrew" refers to the servant (and not to the master); here, too, "Hebrew" refers to the servant (and not to the master). And though there is no proof for this (i.e., that "servant Hebrew" is to be understood as "a servant who is a Hebrew" (and not as "the servant of a Hebrew"), there is support for it, viz. (Exodus 5:3) "The G d of the Hebrews revealed Himself to us" — (the G d) of "Avram the Hebrew" (Genesis 14:13).

2) And whence is it derived that ona'ah does not apply to bondsmen? From (Devarim 15:46) "And you shall hold them (bondsmen) for your sons after you as an inheritance of holding" — Just as ona'ah does not apply to a "holding" (land), so, it does not apply to bondsmen.

5) (Vayikra 25:46) ("And you shall hold them as an inheritance for your sons after you to inherit as a holding. Forever shall you have them serve you. And in your brothers, the children of Israel, one man in his brother, you shall not rule over him oppressively.") "And you shall hold them as an inheritance (for your sons). "them" (the servants) for your sons and not your daughters for your sons — whence we are taught that a father does not pass on his (rights in his) daughters to his sons. And whence is it derived that one who is regarded de facto as one's son is considered his son (for all purposes)? From ("your sons) after you," ("after you" connoting "who are regarded as yours.") "as a holding": Just as (the halachah of) ona'ah ("wronging") does not obtain with a (field of) holding (viz. Vayikra 25:14), so, it does not obtain with servants.

6) "Forever shall you have them serve you.": You have in them only (rights of) service, (but not "rights" of oppression). "And in your brothers, the children of Israel, one man in his brother": This tells me only of a man vis-à-vis a man. Whence do I derive the same for a man vis-à-vis a woman, a woman vis-à-vis a man, a woman vis-à-vis a woman? From "one man in his brother" — in any event (of "brotherhood). "you shall not rule over him oppressively": "you shall not rule over him oppressively," but you may rule over a free man, (who hires himself out for hard labor) "oppressively."

R. Simeon the son of Lakish maintained: Shem’s descendants also became slaves, as it is said: And if thy brother, a Hebrew man or a Hebrew woman, be sold unto thee (Deut. 15:12). Shem’s descendants, however, are freed at the expiration of six years, of servitude, as it is written: Then in the seventh year thou shalt let him go free (ibid.), while the descendants of Ham are never freed, as is said: You may hold them to service forever (Lev. 25:46). Therefore, he remains a lifelong slave and does not go forth into the world a free man. Why was this curse imposed upon him? Because he was responsible for his father’s degradation. Thus, the Holy One, blessed be He, brought retribution upon the descendants of Ham by humiliating them by means of the king of Asshur, as it is said: So shall the king of Assyria lead away the captives of Egypt and the exiles of Ethiopia, young and old, naked and barefoot (Isa. 20:4).

R. Yishmael says: A Canaanite man-servant can never be redeemed and can go free only by consent (of the master), as it is written (Leviticus 25:46) "And you shall hold them as an inheritance … to inherit as a holding, etc." And in our manner we have learned that a Canaanite man-servant is like a field of holding forever. But if his master persecuted him and knocked out his tooth or blinded his eye or (maimed) one of his (other) external organ prominences, he acquires himself (i.e., his freedom) with afflictions. Now does this not follow a fortiori, viz.: If one can acquire himself by afflictions from the hand of flesh and blood, how much more so, from the hands of Heaven! And thus is it written (Psalms 118:18) "The L rd has afflicted me exceedingly and He did not consign me to death."