Genesis 21

The Birth of Isaac

1 Then the LORD did exactly what he had promised.

Jehovah keeps His word! God fulfilled his promise to Sarah by giving her, at the advanced age of ninety, power to conceive and bring forth a son.

2 Sarah became pregnant, and she gave a son to Abraham in his old age. It all happened at the time God had said it would.

The birth of Isaac marked a pivotal point in the outworking of God’s eternal purpose. The coming of this son to Abraham and Sarah was the second great step toward the fulfillment of Jehovah’s plan. This purpose and plan was to have a people of His own, separate from the surrounding nations; a people to whom should be entrusted the Holy Oracles, a people of whom as concerning the flesh the Savior was to be born; a people who should ultimately become the medium of blessing to all the earth. In the realization of this plan and purpose the first great step was the selection of Abram to be the father of the chosen nation, the call which separated him from the idolatrous people among whom he lived, and the migration unto the land which Jehovah promised to give him.

The birth of Christ foreshadowed Isaac’s birth in 7 ways:
1. Isaac was the promised seed and son:
a. Genesis 17:16 - And I will bless her and give you a son from her! Yes, I will bless her richly, and she will become the mother of many nations. Kings will be among her descendants!
b. So was Christ
i. Genesis 3:15 - From now on, you and the woman will be enemies, and your offspring and her offspring will be enemies. He will crush your head, and you will strike his heel.
ii. Isaiah 7:14 - All right then, the Lord himself will choose the sign. Look! The virgin will conceive a child! She will give birth to a son and will call him Immanuel--`God is with us.'
2. A lengthy interval occurred between God’s first promise to Abraham and its realization. When we are told, Then the LORD did exactly what he had promised " (Genesis 21:1), the immediate reference is to Genesis 17:16 and Genesis 18:14, but the remote reference was to the original promise of Genesis 12:7. So also was there a lengthy interval between God’s promise to send Christ and the actual fulfillment of it.
3. When Isaac’s birth was announced, his mother asked, Can an old woman like me have a baby? (Genesis 18:13), to which the answer was returned, "Is anything too hard for the Lord?" and the striking analogy is seen in the fact that when the angel of the Lord made known unto Mary that she was to be the mother of the Savior, she asked, But how can I have a baby? I am a virgin. (Luke 1:34), to which query the answer was returned, nothing is impossible with God. (Luke 1:37): so that in each case God’s omnipotency was affirmed following the annunciation of the birth of the child.
4. Isaac’s name was specified before he was born — You will name him Isaac (Genesis 17:19); compare with this the words of the angel to Joseph before Christ was born — … you are to name him Jesus (Matthew 1:21)!
5. Isaac’s birth occurred at God’s appointed time (Genesis 21:2) at the set time; so also in connection with the Lord Jesus we read But when the right time came, God sent his Son, born of a woman, subject to the law. (Galatians 4:4).
6. As we have seen above, Isaac’s birth required a miracle to bring it about; so also was it with the incarnation of Immanuel.
7. The name Isaac (given unto him by Abraham and not Sarah, Genesis 21:3), which means laughter, declared him to be his father’s delight; so also was the one born at Bethlehem — This is my beloved Son, and I am fully pleased with him.

3 And Abraham named his son Isaac.

Galatians 4:22-31: The Scriptures say that Abraham had two sons, one from his slave-wife and one from his freeborn wife. The son of the slave-wife was born in a human attempt to bring about the fulfillment of God's promise. But the son of the freeborn wife was born as God's own fulfillment of his promise. Now these two women serve as an illustration of God's two covenants. Hagar, the slave-wife, represents Mount Sinai where people first became enslaved to the law. And now Jerusalem is just like Mount Sinai in Arabia, because she and her children live in slavery. But Sarah, the free woman, represents the heavenly Jerusalem. And she is our mother. That is what Isaiah meant when he prophesied,
"Rejoice, O childless woman!
Break forth into loud and joyful song,
even though you never gave birth to a child.
For the woman who could bear no children
now has more than all the other women!"
And you, dear brothers and sisters, are children of the promise, just like Isaac. And we who are born of the Holy Spirit are persecuted by those who want us to keep the law, just as Isaac, the child of promise, was persecuted by Ishmael, the son of the slave-wife. But what do the Scriptures say about that? "Get rid of the slave and her son, for the son of the slave woman will not share the family inheritance with the free woman's son." So, dear brothers and sisters, we are not children of the slave woman, obligated to the law. We are children of the free woman, acceptable to God because of our faith.

4 Eight days after Isaac was born, Abraham circumcised him as God had commanded.

5 Abraham was one hundred years old at the time.

6 And Sarah declared, "God has brought me *laughter! All who hear about this will laugh with me.

*laughter – Isaac means “laughter”.

7 For who would have dreamed that I would ever have a baby? Yet I have given Abraham a son in his old age!"

8 As time went by and Isaac grew and was weaned, Abraham gave a big party to celebrate the happy occasion.
When the period for weaning him arrived, the patriarch made, after the manner of those times, a great feast. We can scarcely say what the age of the child was, - whether one year, or, as Josephus implies, three years old.

9 But Sarah saw Ishmael--the son of Abraham and her Egyptian servant Hagar--making fun of Isaac.

Ishmael must have been at least fifteen, and possibly seventeen years of age.

10 So she turned to Abraham and demanded, "Get rid of that servant and her son. He is not going to share the family inheritance with my son, Isaac. I won't have it!"

11 This upset Abraham very much because Ishmael was his son.

12 But God told Abraham, "Do not be upset over the boy and your servant wife. Do just as Sarah says, for Isaac is the son through whom your descendants will be counted.

13 But I will make a nation of the descendants of Hagar's son because he also is your son."

14 So Abraham got up early the next morning, prepared food for the journey, and strapped a container of water to Hagar's shoulders. He sent her away with their son, and she walked out into the wilderness of *Beersheba, wandering aimlessly.

*Beersheba – Beersheba was the southernmost city of Israel. It is about 45 miles southwest of Jerusalem in the Negeb. Beersheba’s southern location and the presence of several wells in the area may explain why Abraham settled there. God confirmed the promises made to Abraham with his son Isaac at Beersheba, where Isaac's servants dug another well, called "Shibah," meaning "an oath" (Genesis 26:23-25). At a later date, Jacob stole Esau's birthright while his family was camped at Beersheba (Genesis 27); he then left Beersheba and traveled to Haran in Mesopotamia to find a wife (Genesis 28:10). Many years later, Beersheba was a stopping place for Jacob when he was told by God to continue on to Egypt where Joseph was awaiting him (Genesis 46:1-5).

15 When the water was gone, she left the boy in the shade of a bush.

16 Then she went and sat down by herself about a *hundred yards away. "I don't want to watch the boy die," she said, as she burst into tears.

*hundred yards - Hebrew “a bowshot”

17 Then God heard the boy's cries, and the angel of God called to Hagar from the sky, "Hagar, what's wrong? Do not be afraid! God has heard the boy's cries from the place where you laid him.

18 Go to him and comfort him, for I will make a great nation from his descendants."

19 Then God opened Hagar's eyes, and she saw a well. She immediately filled her water container and gave the boy a drink.

20 And God was with the boy as he grew up in the wilderness of Paran. He became an expert archer,

21 and his mother arranged a marriage for him with a young woman from Egypt.

22 About this time, *Abimelech came with Phicol, his army commander, to visit Abraham. "It is clear that **God helps you in everything you do," Abimelech said.

*Abimelech – Is this the same Abimelech of Genesis 20? It isn't the same. Abimelech is the title of a ruler among the Canaanites, not a specific name.

**God helps you in everything you do – Look at how Abraham influenced Abimelech. Do our lives have this kind of impact on others? As with Abimelech, others are watching us and making judgments not only about us but also about our God and Lord.

23 "Swear to me in God's name that you won't *deceive me, my children, or my grandchildren. I have been loyal to you, so now swear that you will be loyal to me and to this country in which you are living."

*deceive – Abraham had deceived him before about Sarah.

Abimelech sought a treaty with Abraham because he did not ever wish to go to battle against him. To fight Abraham was to attack Abraham’s God. On the other hand, to have an alliance with Abraham was to have God on his side.

24 Abraham replied, "All right, I swear to it!"

25 Then Abraham complained to Abimelech about a well that Abimelech's servants had taken violently from Abraham's servants.

26 "This is the first I've heard of it," Abimelech said. "And I have no idea who is responsible. Why didn't you say something about this before?"

27 Then Abraham gave sheep and oxen to Abimelech, and they made a treaty.

28 But when Abraham took seven additional ewe lambs and set them off by themselves,

29 Abimelech asked, "Why are you doing that?"

30 Abraham replied, "They are my gift to you as a public confirmation that I dug this well."

31 So ever since, that place has been known as Beersheba--"well of the oath"--because that was where they had sworn an oath.

32 After making their covenant, Abimelech left with Phicol, the commander of his army, and they returned home to the land of the Philistines.

33 Then Abraham planted a *tamarisk tree at Beersheba, and he worshiped the LORD, the **Eternal God, at that place.


Near the outer gate of Beersheba is a well and a *tamarisk tree. Both are later than the time of the patriarchs, but they remind one of the well Abraham dug and the tree he planted.
The tamarisk tree is well suited to life in the Negev with its deep root system and its ability to survive on brackish water. It secretes salt on its leaves and drips water in the morning.


**Eternal God – “Jehovah, El-Olam” – “Jehovah is the eternal God”.

34 And Abraham lived in Philistine country for a long time.