"His offspring will be mighty in the land." What is the reward for this? "His offspring will be mighty in the land" - this refers to Isaac, as it is said, "For through Isaac shall your offspring be named" (Genesis 21:12). And what was his strength? He prayed for his wife to conceive, as it is said, "And Isaac prayed to the Lord on behalf of his wife" (Genesis 25:21). Is there a greater strength than this, that he prayed for an infertile woman to conceive?
Another explanation: "His offspring will be mighty in the land." This refers to Jacob, as it is said, "But now thus says the Lord, he who created you, O Jacob, he who formed you, O Israel: 'Fear not, for I have redeemed you; I have called you by name, you are mine'" (Isaiah 43:1). And what was his strength? He wrestled with the angel and prevailed, as it is said, "And Jacob wrestled with the angel" (Hosea 12:5). "May the righteous flourish in their days" (Psalm 72:7) - these are the twelve tribes of Israel.