John Calvin Commentary Isaiah 63:12

"that caused his glorious arm to go at the right hand of Moses? that divided the waters before them, to make himself an everlasting name?" — Isaiah 63:12 (ASV)

Who led them. Here he continues to describe the miraculous deliverance of the people, who were led out of Egypt under the guidance of Moses, and he also relates the complaints that might arise in the minds of the afflicted Jews.

In this, we see two things connected: namely, the right hand of Moses and the arm of God’s majesty. The Lord employs the labors and ministry of men in such a way that his praise and glory must not be diminished or obscured in any degree, for while these things are transacted under Moses as the leader, everything is ascribed to God.

Just as when the ministers of the Gospel are said to forgive sins (John 20:23)—which nevertheless belongs to God alone—does this detract from his authority and majesty? Not at all, for they are only his instruments and lend their labor to God, to whom the undivided praise ought to be rendered. Indeed, what could the hand of a single man have accomplished if it had not been wielded by the arm of God?

Accordingly, he expressly adds the purpose: that God performed miracles at that time so that he might gain for himself an everlasting name. And if we are not at liberty to deprive him of this, it is not permissible to transfer to man even the smallest portion of praise.