Genesis 21: The Birth of Isaac and the Covenant with Abimelech

Genesis 21 is a significant chapter in the book of Genesis, marking the fulfillment of God’s promise to Abraham and Sarah with the birth of Isaac. It also describes the expulsion of Hagar and Ishmael, as well as the covenant between Abraham and Abimelech. This chapter highlights God’s faithfulness, human struggles, and the importance of divine promises.

I. Structure of Genesis 21

Genesis 21 can be divided into three main sections:

1. The Birth of Isaac (Verses 1–7) – God's promise to Abraham and Sarah is fulfilled.

2. Hagar and Ishmael Sent Away (Verses 8–21) – Abraham, under Sarah’s insistence, expels Hagar and Ishmael, but God cares for them.

3. Covenant Between Abraham and Abimelech (Verses 22–34) – Abraham and Abimelech make a treaty concerning a well at Beersheba.

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II. Verse-by-Verse Explanation

1. The Birth of Isaac (Genesis 21:1–7)

Verse 1:
"Now the Lord was gracious to Sarah as he had said, and the Lord did for Sarah what he had promised."

This verse emphasizes that God fulfilled His promise to Sarah. It reflects divine faithfulness and reinforces the biblical theme that God always keeps His word.

Verse 2:
"Sarah conceived and bore a son to Abraham in his old age, at the very time God had promised him."

Sarah, once barren, now gives birth to Isaac at the exact time God had determined. This miraculous event proves that God's timing is perfect, even when human expectations seem impossible.

Verse 3:
"Abraham gave the name Isaac to the son Sarah bore him."

The name Isaac means "he laughs," recalling Abraham and Sarah's reactions when they first heard about the promise (Genesis 17:17, 18:12). This name serves as a reminder of both doubt and joy.

Verse 4:
"When his son Isaac was eight days old, Abraham circumcised him, as God commanded him."

Abraham obeys God's covenantal command (Genesis 17:10-12). Circumcision signifies Isaac’s inclusion in God's covenant and foreshadows future obedience expected from God's people.

Verse 5:
"Abraham was a hundred years old when his son Isaac was born to him."

This verse highlights the miraculous nature of Isaac’s birth, as both Abraham and Sarah were well beyond childbearing years.

Verse 6:
"Sarah said, ‘God has brought me laughter, and everyone who hears about this will laugh with me.’"

Sarah acknowledges God's role in her joy. What was once an impossible dream is now a reality, bringing laughter of faith instead of doubt.

Verse 7:
"Who would have said to Abraham that Sarah would nurse children? Yet I have borne him a son in his old age!"

Sarah expresses astonishment, emphasizing the divine intervention in her life. This verse serves as a testimony to God’s ability to accomplish the impossible.

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2. Hagar and Ishmael Sent Away (Genesis 21:8–21)

Verse 8:
"The child grew and was weaned, and on the day Isaac was weaned Abraham held a great feast."

Weaning typically happened when a child was around 2–3 years old. This feast reflects Isaac’s importance as the child of promise.

Verse 9:
"But Sarah saw that the son whom Hagar the Egyptian had borne to Abraham was mocking."

Ishmael (around 16 years old) mocks or ridicules Isaac. The Hebrew word could imply persecution (Galatians 4:29), suggesting that Sarah saw Ishmael as a threat to Isaac’s inheritance.

Verse 10:
"She said to Abraham, ‘Get rid of that slave woman and her son, for that woman’s son will never share in the inheritance with my son Isaac.’"

Sarah insists that Ishmael should not share in Isaac’s inheritance. Her request echoes ancient customs where a firstborn son of a concubine could be disinherited.

Verse 11:
"The matter distressed Abraham greatly because it concerned his son."

Abraham loves Ishmael, and sending him away is heartbreaking. This demonstrates his deep attachment to both his sons.

Verse 12:
"But God said to him, ‘Do not be distressed about the boy and your slave woman. Listen to whatever Sarah tells you, because it is through Isaac that your offspring will be reckoned.’"

God reassures Abraham that Isaac is the chosen heir, fulfilling His covenant promise (Genesis 17:19-21).

Verse 13:
"I will make the son of the slave into a nation also, because he is your offspring."

God promises to bless Ishmael, turning him into a great nation (fulfilled in Genesis 25:12-18). This shows God’s care for all people, not just Isaac’s descendants.

Verse 14:
"Early the next morning, Abraham took some food and a skin of water and gave them to Hagar."

Abraham obeys God, though it is difficult. The provision of minimal supplies highlights the harshness of Hagar’s journey.

Verse 15:
"When the water in the skin was gone, she put the boy under one of the bushes."

Facing dehydration, Hagar places Ishmael under a bush, unable to watch him die.

Verse 16:
"Then she went off and sat down about a bowshot away, for she thought, ‘I cannot watch the boy die.’"

Hagar's despair reaches its peak, emphasizing her helplessness.

Verse 17:
"God heard the boy crying, and the angel of God called to Hagar from heaven, ‘What is the matter, Hagar? Do not be afraid; God has heard the boy crying as he lies there.’"

God responds with compassion, reaffirming His promise to Ishmael.

Verse 18:
"Lift the boy up and take him by the hand, for I will make him into a great nation."

God renews His promise, demonstrating His faithfulness.

Verse 19:
"Then God opened her eyes and she saw a well of water."

A miraculous provision of water saves their lives, showing God as a provider.

Verse 20-21:
"God was with the boy as he grew up... He lived in the desert and became an archer."

Ishmael grows under God’s protection, fulfilling His promise of making him a great nation.

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3. Covenant Between Abraham and Abimelech (Genesis 21:22–34)

Verse 22-23:
Abimelech seeks a peace treaty with Abraham, recognizing God’s favor upon him.

Verse 24:
Abraham agrees, demonstrating his commitment to peace.

Verses 25-26:
A dispute arises over a well, showing that land ownership was a serious issue even in ancient times.

Verses 27-30:
Abraham gives Abimelech seven ewe lambs as proof of ownership of the well.

Verse 31:
The place is named Beersheba, meaning "Well of the Oath."

Verse 33:
"Abraham planted a tamarisk tree in Beersheba, and there he called on the name of the Lord, the Eternal God."

This act symbolizes worship and acknowledgment of God's eternal nature.

Verse 34:
Abraham continues dwelling in the land peacefully, awaiting further fulfillment of God's promises.

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III. Theological Themes and Lessons

1. God’s Faithfulness – The birth of Isaac proves that God's promises never fail.

2. Divine Providence – God's care for Ishmael shows that He is concerned for all people.

3. Covenantal Inheritance – Isaac, not Ishmael, is the heir of God’s covenant.

4. God as Provider – Hagar’s rescue shows God’s provision in times of despair.

5. Peace and Diplomacy – Abraham’s treaty with Abimelech highlights the importance of peaceful relations.

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Genesis 21 is a powerful testimony of God’s faithfulness, His care for all people, and the unfolding of His redemptive plan.