Charles Spurgeon Commentary Isaiah 51:1-2

"Hearken to me, ye that follow after righteousness, ye that seek Jehovah: look unto the rock whence ye were hewn, and to the hold of the pit whence ye were digged. Look unto Abraham your father, and unto Sarah that bare you; for when he was but one I called him, and I blessed him, and made him many." — Isaiah 51:1-2 (ASV)

This is for your comfort, dear friends. If God could make from Abraham and Sarah so great a nation as Israel, what is there that he cannot do?

Do you say that the cause of God is brought very low in these evil days? It is not as low as when there seemed to be no one but Abraham faithful in the whole world. Yet God made that one mighty man to be like a foundation upon which he built up the chosen people, to whose keeping he committed the sacred oracles. And if he did that, what can he not do?

However low you may individually sink, or however weak you may feel, look back to Abraham, and learn from his experience what God can do with you.