Isaiah 51:5

My righteousness is near - The word ‘righteousness’ is used in a great variety of significations. Here it means, probably, the faithful completion of his promises to his people (Lowth).

My salvation is gone forth - The promise of salvation is gone forth, and already the execution of that purpose is commenced. He would soon deliver his people; he would at no distant period extend salvation to all nations.

And mine arm shall judge the people - That is, shall dispense judgment to them. The ‘arm’ here is put for himself, as the arm is the instrument by which we execute 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 would become interested in the true religion, and acknowledge and worship the true God.