Midras Ulangan 15:17: Mekhilta DeRabbi Yishmael, Midrash Tanchuma, Midrash Tanchuma Buber & Sifrei Devarim

"and he shall bring him near to the door or to the door-post": The door is being compared to the door-post, viz.: Just as a door-post stands in its place, so, the door must be standing in its place. And this would follow a fortiori, viz.: If the door, which is not kasher for the mitzvah (of mezuzah), is kasher for boring, then the door-post, which is kasher for the mitzvah of mezuzah, how much more so should it be kasher for boring! It is, therefore, written (Devarim 15:17) "Then you shall take the awl and place it in his ear and in the door" — You place it in the door, but not in the door-post. But perhaps the awl is to pierce both his ear and the door-post; it is, therefore, written (Exodus 21:6) "then his master shall bore his ear with an awl" — his ear is pierced and not the door. It is the first reading, then, which is to be accepted — The door is being compared to the door-post, viz.: Just as a door-post stands in its place, so, the door must be standing in its place.

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).

(Gen. 9:25:) AND HE SAID: CURSED BE CANAAN. Ham looked; is Canaan cursed?⁸³Gen. R. 36:7. R. Judah said: The curse does not coexist with a blessing. < Ham could not be cursed > because it is stated (in Gen. 9:1): THEN GOD BLESSED [NOAH AND HIS CHILDREN. R. Nehemiah said:] Canaan had looked and told his father; so the curse had returned to its source. For that reason it is stated (in Gen. 9:25): CURSED BE CANAAN. Our masters have said: When Noah was in the ark, he said: Oh, that my children had slaves so that, while they were seated, those < slaves > would go forth before them. When, however, I go out from the ark, whomever I beget I shall make into slaves for them. He said to him (Ham): You did not allow me to beget a fourth son who would be a slave for his brothers.⁸⁴See Sanh. 70a, according to which Rav maintained that Ham had castrated his father. By your life, I am making your fourth son a slave. Thus it stated (in Gen. 9:25): AND HE SAID: CURSED BE CANAAN; [A SLAVE OF SLAVES SHALL HE BE TO HIS BROTHERS]. Resh Laqish said: Behold, those from Ham are slaves forever, but the children of Shem go forth into the world free. Thus it is stated (in Deut. 15:12, 17): IF THERE IS SOLD TO YOU < A FELLOW HEBREW, MAN OR WOMAN … IN THE SEVENTH YEAR YOU SHALL SET HIM FREE >…. THEN YOU SHALL TAKE AN AWL < AND PUT IT THROUGH HIS EAR INTO THE DOOR >. What is written there (in vs. 17)? AND HE SHALL BE YOUR SLAVE FOREVER. Here, however, is a slave of slaves, < i.e., > a slave who does not take his freedom and never goes away. What caused this curse for him? < It came about > because he had treated his father with contempt. So also the Holy One is going to exact punishment from the children of Ham and humiliate them at the hands of the king of Assyria, as stated (in Is. 20:4): SO SHALL THE KING OF ASSYRIA DRIVE OFF < THE CAPTIVES OF EGYPT AND THE EXILES OF NUBIA > … [NAKED AND BAREFOOT]. What is the meaning of NAKED AND BAREFOOT? That he would humiliate them and parade them naked. Now, in regard to Japheth, who honored his father, how does the Holy One repay him? When Gog (Japheth's descendant) comes, the Holy One will overshadow him and cover him over, as stated (in Ezek. 39:11): AND IT SHALL COME TO PASS IN THAT DAY THAT I WILL GIVE UNTO GOG A BURIAL PLACE THERE IN ISRAEL. And how did he reward Shem? When the sons of Aaron came in to offer sacrifice, their bodies (according to Lev. 10:2) were burned but their clothes were not burned.⁸⁵Cf. Shab. 113b; Sanh. 52a, according to which their bodies were not burned. Why? Because they were children of Shem. That is how it is with the righteous. But where is it shown about the wicked? When Sennacherib went up to Jerusalem, and all his soldiers with him, their bodies were burned and their clothes were not burned. Why? Because they were children of Shem, as stated (in Gen. 10:22): THE SONS OF SHEM ARE ELAM, ASSHUR, ARPACHSHAD, LUD, AND ARAM.