John Calvin Commentary Isaiah 51:5

"My righteousness is near, my salvation is gone forth, and mine arms shall judge the peoples; the isles shall wait for me, and on mine arm shall they trust." — Isaiah 51:5 (ASV)

My righteousness is near. He confirms the former doctrine. The “righteousness” of the Lord relates to people, who know by experience that he is “righteous.” While the people were oppressed by cruel bondage, they indeed knew that they were justly punished for their sins; but they might wonder why they were so forsaken, because the worship of God ceased, and his name was blasphemed by wicked men, who pursued their wicked ways without punishment.

Therefore, to bring them some consolation, he promises that God will speedily assist them, so that all will acknowledge that he is faithful and just. By the word “righteous” the Prophet does not mean that he gives to everyone a “righteous” reward, but that he provides the best protection and shows the greatest kindness to his people, faithfully performing his promises to all believers when he delivers them and does not allow them to be ultimately overwhelmed.

This appears more clearly from the following clause, where, for explanation, he adds, My salvation has gone forth; for the “righteousness” of God shone brightly in the deliverance of the people. Now, the captivity in which the Jews were held in Babylon was a kind of death; consequently, that deliverance is here called “Salvation.”

My arms shall judge the peoples. By “arms” he means the wide exercise of his power. That figure of speech which describes God using expressions drawn from the human body occurs frequently in Scripture. Because God’s government appeared to be confined within narrow limits, or rather was not at all visible, for this reason he mentions arms, by which he means that he will spread his kingdom far and wide.