מוֹלִיךְ֙ לִימִ֣ין מֹשֶׁ֔ה זְר֖וֹעַ תִּפְאַרְתּ֑וֹ בּ֤וֹקֵֽעַ מַ֙יִם֙ מִפְּנֵיהֶ֔ם לַעֲשׂ֥וֹת ל֖וֹ שֵׁ֥ם עוֹלָֽם׃
Rashi on Isaiah
He led at Moses’ right the arm of His glory The Holy One, blessed be He, led at Moses’ right the arm of His might. Every time he required the aid of the Holy One, blessed be He, His arm was ready at his right.
Ibn Ezra on Isaiah
His glorious arm: His angel, that went before the camp of Israel (Ex. 14:19)