Hebrews 11:11-12

By faith Abraham, even though he was past age--and Sarah herself was barren--was enabled to become a father because he considered him faithful who had made the promise. And so from this one man, and he as good as dead, came descendants as numerous as the stars in the sky and as countless as the sand on the seashore.

By faith Abraham, even though he was past age--and Sarah herself was barren
Genesis 17:17-19 Abraham fell face down; he laughed and said to himself, "Will a son be born to a man a hundred years old? Will Sarah bear a child at the age of ninety?" And Abraham said to God, "If only Ishmael might live under your blessing!" Then God said, "Yes, but your wife Sarah will bear you a son, and you will call him Isaac. I will establish my covenant with him as an everlasting covenant for his descendants after him."
Genesis 18:11-14 Abraham and Sarah were already old and well advanced in years, and Sarah was past the age of childbearing. So Sarah laughed to herself as she thought, "After I am worn out and my master is old, will I now have this pleasure?" Then the LORD said to Abraham, "Why did Sarah laugh and say, 'Will I really have a child, now that I am old?' Is anything too hard for the LORD? I will return to you at the appointed time next year and Sarah will have a son."

was enabled to become a father
Genesis 21:2 Sarah became pregnant and bore a son to Abraham in his old age, at the very time God had promised him.

because he considered him faithful who had made the promise
1 Corinthians 1:9 God, who has called you into fellowship with his Son Jesus Christ our Lord, is faithful.

And so from this one man, and he as good as dead
Romans 4:19 Without weakening in his faith, he faced the fact that his body was as good as dead--since he was about a hundred years old--and that Sarah's womb was also dead.

came descendants as numerous as the stars in the sky and as countless as the sand on the seashore
Genesis 22:17-18 "I will surely bless you and make your descendants as numerous as the stars in the sky and as the sand on the seashore. Your descendants will take possession of the cities of their enemies, and through your offspring all nations on earth will be blessed, because you have obeyed me."

NOTES:
Genesis 11:30; 13:16; 15:5; 21:5; 26:4; 1 Kings 4:20
Read Ephesians 6

Scriptures taken from the Holy Bible, New International Version® NIV®, Copyright© 1973, 1978, 1984 by International Bible Society. Used by permission. All rights reserved worldwide.