Gen 9:22–24: he saw the nakedness; they covered it

Says וַיַּרְא חָם אֲבִי כְנַעַן אֵת עֶרְוַת אָבִיו, "and Ham, the father of Canaan, saw the nakedness ('ervah) of his father," וַיַּגֵּד לִשְׁנֵי־אֶחָיו בַּחוּץ, "and told his two brothers outside." Shem and Japheth take הַשִּׂמְלָה, "the garment" (BDB "wrapper, mantle"), walk אֲחֹרַנִּית, "backward," and cover it (BDB "cover"); וְעֶרְוַת אֲבִיהֶם לֹא רָאוּ, "and their father's nakedness they did not see." "Nakedness" stands three times.

Says In 9:24 וַיִּיקֶץ נֹחַ מִיֵּינוֹ, "and Noah awoke from his wine" (BDB "awake"; "from his drunkenness," BSB), and knew what בְּנוֹ הַקָּטָן, "his small son," had done (BDB "small, young, unimportant").

Implies The sin of 8:21 goes on after the flood: the first story after the covenant shows drunkenness and a son's offense.

Uncertain (1) What Ham did: (a) looked and told, a dishonor; (b) a sexual act against Noah, reading "saw the nakedness" by the idiom of Lev 18 and 20; (c) an act with Noah's wife (Lev 18:7–8; 20:11); (d) castration, a rabbinic reading. Against (a): "what his small son had done to him" (9:24) suggests an act; against (b)–(d): the text says only "saw" and "told." 9:23, where the brothers do not see, is read by (a) as the answer to Ham's looking and by the others as covering what was done. (2) Whether the "small son" is Ham or Canaan. No lean is taken here.