Rashi on Genesis 9:24/רש"י על בראשית ט׳:כ״ד

1בנו הקטן HIS YOUNGER SON — The unworthy and despicable one, as (Jeremiah 49:15) “For, behold, I make thee small (קטן) among the nations, and despised among men" (Genesis Rabbah 36:7).