Albert Barnes 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 – The word ‘righteousness’ is used in a great variety of meanings. Here it means, probably, the faithful completion of His promises to His people (Lowth).

My salvation is gone forth – The promise of salvation has gone forth, and the execution of that purpose has already begun. He will soon deliver His people; He will before long extend salvation to all nations.

And mine arm shall judge the people – That is, it will dispense judgment to them. The ‘arm’ here represents Him, as the arm is the instrument by which we carry out our purposes (see the notes at Isaiah 51:9).

The isles shall wait upon me – The distant nations; the pagan lands (see the note at Isaiah 41:1). The idea is that distant lands will become interested in the true religion, and acknowledge and worship the true God.