In Isaiah, chapter forty-one, verse eight, “But thou, Israel, art my servant, Jacob whom I have chosen, the seed of Abraham my friend.” The nation of God must not fear destruction, because God chose them as His channel to carry out the promise of redemption He had made to their ancestors. Through the nation of Israel would come both the Messiah and the written revelation of God, by which salvation would go to all nations of the earth.
This is an address directly to the people of God and is designed to show them, in view of the truths which had just been urged, that God was their protector and friend. Those who relied on idols were trusting in that which could not aid them. But those who trusted in Him were safe. For their protection, he had raised Cyrus for this purpose: he had subdued the nations before him. God now expresses to them the assurance, although the nations should be destroyed, yet that He had chosen them, and would remember them, and His promise made to Abraham, their illustrious ancestor.
The descendants of Jacob, whom I have selected to be my people. Abraham, my friend. Abraham was regarded as the friend of God, ‘And he was called the Friend of God,’ as in James two, verse twenty-three. This most honorable appellation he deserved by a life of devoted piety and by habitually submitting himself to the will of God. The idea in this verse is that, as they were the descendants of his friend, God deemed himself bound to protect and deliver them according to his gracious promises; and this is one of the many instances where the divine favor is manifested to descendants in consequence of the piety and prayers of their ancestors in the Old Testament.