Isaiah 48:9

Even though Israel had been prone to idolatry (Isaiah 48:5) and had been congenitally rebellious (Isaiah 48:8), God had not cast her off. Why? He had made commitments to be gracious to Israel, and to honor Himself in His dealings with her, so that the rest of the world would trust Him. The fact that God did not abandon Israel when He could have done so justly manifested His grace.