וּלְשֵׁ֥ם יֻלַּ֖ד גַּם־ה֑וּא אֲבִי֙ כָּל־בְּנֵי־עֵ֔בֶר אֲחִ֖י יֶ֥פֶת הַגָּדֽוֹל׃
Scem ebbe anch’egli [numerosa] discendenza; egli, che fu il progenitore di tutti i [cosiddetti] transfluviani [popoli di là dell’Eufrate]; egli che del fratel maggiore, Jèfeth, fu [il condegno] fratello.
Rashi on Genesis
אבי כל בני עבר THE FATHER OF ALL THE CHILDREN OF EBER — (עבר means the “side” or “ other side” of a river) — The father of all the children of עבר הנהר, the other side of the River (Euphrates), was Shem.
Ramban on Genesis
AND UNTO SHEM, TO HIM ALSO WERE CHILDREN BORN. Since Scripture delayed the narration of the generations of Shem and related the generations of his younger brother as if Shem had no children, it therefore says here, to him also.
Sforno on Genesis
ולשם יולד, the formulation suggests that the son born to Shem resembled his father in his good qualities, the son in question being עבר.