Midras Yesaya 20:4: Midrash Tanchuma, Midrash Tanchuma Buber & Bereshit Rabbah

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.

“Shem and Yefet took the garment, they placed it upon the shoulders of both of them, they walked backward, and they covered the nakedness of their father and they faced backward, and they did not see the nakedness of their father” (Genesis 9:23).
“Shem and Yefet took the garment” – Rabbi Yoḥanan said: Shem began with the mitzva first, and Yefet came and heeded him.³²He heeded Shem’s request to help him. That is why he [Shem] merited the prayer shawl³³Shem is the ancestor of Israel. and Yefet, the regal cloak.
“They placed it upon the shoulders of both of them, they walked backward, and they covered the nakedness of their father.” From the fact that it is stated: “They walked backward,” do I not know that “they did not see the nakedness of their father”? Rather, it teaches that they placed their hands over their faces as they were walking backward, conducting themselves with respect, in keeping with the [appropriate] reverence for a father upon his son. The Holy One blessed be He said to Shem: ‘You covered your father’s nakedness, by your life, I will repay you, [as it is written]: “Then these men³⁴Ḥananya, Mishael and Azaria, who were descendants of Shem. were bound in their sarbaleihon […and were thrown into the fiery furnace]”’ (Daniel 3:21). [What is sarbaleihon?] Rabbi Yudan and Rabbi Huna, Rabbi Yudan said: Their cloaks. Rabbi Huna said: Their robes.³⁵They were not stripped of their garments when thrown into the furnace, in the merit of their ancestor Shem.
The Holy One blessed be He said to Yefet: ‘You covered your father’s nakedness, by your life, I will repay you [as it is written]: “It will be on that day, I will give Gog³⁶Gog is the king of the nation of Magog, who are descendants of Yefet (Genesis 10:2). a place of burial there, in Israel, the valley of the passersby east of the sea, and it will block the passersby, and they will bury Gog and all his multitude there, and they will call it the valley of the Multitude of Gog”’ (Ezekiel 39:11).³⁷Just as Yefet covered Noah’s body, so will the bodies of his descendants be covered up, in burial.
The Holy One blessed be He said to Ḥam: ‘You brought shame to your father’s nakedness, by your life, I will exact retribution against you: “So the king of Assyria will lead the captives of Egypt and the exiles of Kush, youths and elders, naked and barefoot and bared of buttocks, the nakedness of Egypt”’ (Isaiah 20:4).³⁸Egypt (Mitzrayim) and Kush were descendants of Ḥam (Genesis 10:6).