Charles Ellicott Commentary Isaiah 42:8-9

"I am Jehovah, that is my name; and my glory will I not give to another, neither my praise unto graven images. Behold, the former things are come to pass, and new things do I declare; before they spring forth I tell you of them." — Isaiah 42:8-9 (ASV)

I am the Lord.... —The prophet grasps the full meaning of the name revealed in Exodus 3:15. It follows from that meaning that God cannot look with indifference on the transfer to the “graven image” of the worship due to Him.

With his vision of Cyrus still present to his thoughts, the prophet again presses the unique point of prediction as distinguishing the religion of Israel from that of the Gentiles. The “former things” refer probably not to the remote past, but to Isaiah’s earlier prophecies, say the whole Assyrian cycle, on which he now looks back from his new standpoint; or even, as in Isaiah 41:22, to the near future of the conquests of Cyrus as compared with that which was to usher in the restoration of Israel.