Midrash su Levitico 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.