Rashi on Isaiah
As many wondered As many peoples wondered about them when they saw them in their humble state, and said to one another, How marred is his [Israel’s] appearance from that of a man! See how their features are darker than those of other people, so, as we see with our eyes.
Ibn Ezra on Isaiah
שממו Were astonished. Comp. ושממו and shall be astonished (Lev. 26:32). Every one will be surprised at the sight of the servant of the Lord.