Sforno on Genesis 9:22/ספורנו על בראשית ט׳:כ״ב

1וירא חם אבי כנען את ערות אביו, he saw the shameful deed his son כנען had done to his father Noach when he had castrated him. (according to some of our sages in Sanhedrin 70) According to the historian Berussi Hacaldaii, (compare Genesis 6,9) Canaan castrated his grandfather not surgically, but by some means of sorcery. His father Cham watched his son invoke the witchcraft without protesting or trying to stop him. Disgrace, shame, is also called ערוה, “nakedness.” Compare Ezra 4,14 וערות מלכא לא אריך לנא למחזא “it is not right that we should see the king being disgraced.” Also, in Deuteronomy 24,1 the expression ערות דבר does not refer to either literal nakedness, or to sexual licentiousness, or incest, but refers to “a disgraceful thing.”

2ויגד לשני אחיו בחוץ, he revealed that he had enjoyed what his son had done.