Charles Spurgeon Commentary Isaiah 48:3

"I have declared the former things from of old; yea, they went forth out of my mouth, and I showed them: suddenly I did them, and they came to pass." — Isaiah 48:3 (ASV)

There is no better proof that God is God than that his prophecies have been fulfilled. Only the eternal can see into the future. He has done so, and every word of his either has been fulfilled, or will yet be fulfilled.