Genesis 21

The LORD visited Sarah as he had said, and the LORD did to Sarah as he had spoken.

Sarah conceived, and bore Abraham a son in his old age, at the set time of which God had spoken to him.

Abraham called his son who was born to him, whom Sarah bore to him, Isaac.

Abraham circumcised his son, Isaac, when he was eight days old, as God had commanded him.

Abraham was one hundred years old when his son, Isaac, was born to him.

Sarah said, “God has made me laugh. Everyone who hears will laugh with me.”

She said, “Who would have said to Abraham that Sarah would nurse children? For I have borne him a son in his old age.”

The child grew and was weaned. Abraham made a great feast on the day that Isaac was weaned.

Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, mocking.

Therefore she said to Abraham, “Cast out this servant and her son! For the son of this servant will not be heir with my son, Isaac.”

The thing was very grievous in Abraham’s sight on account of his son.

God said to Abraham, “Don’t let it be grievous in your sight because of the boy, and because of your servant. In all that Sarah says to you, listen to her voice. For your offspring will be named through Isaac.

I will also make a nation of the son of the servant, because he is your child.”

Abraham rose up early in the morning, and took bread and a container of water, and gave it to Hagar, putting it on her shoulder; and gave her the child, and sent her away. She departed, and wandered in the wilderness of Beersheba.

The water in the container was spent, and she put the child under one of the shrubs.

She went and sat down opposite him, a good way off, about a bow shot away. For she said, “Don’t let me see the death of the child.” She sat opposite him, and lifted up her voice, and wept.

God heard the voice of the boy. The angel of God called to Hagar out of the sky, and said to her, “What troubles you, Hagar? Don’t be afraid. For God has heard the voice of the boy where he is.

Get up, lift up the boy, and hold him with your hand. For I will make him a great nation.”

God opened her eyes, and she saw a well of water. She went, filled the container with water, and gave the boy a drink.

God was with the boy, and he grew. He lived in the wilderness, and as he grew up, he became an archer.

He lived in the wilderness of Paran. His mother got a wife for him out of the land of Egypt.

At that time, Abimelech and Phicol the captain of his army spoke to Abraham, saying, “God is with you in all that you do.

Now, therefore, swear to me here by God that you will not deal falsely with me, nor with my son, nor with my son’s son. But according to the kindness that I have done to you, you shall do to me, and to the land in which you have lived as a foreigner.”

Abraham said, “I will swear.”

Abraham complained to Abimelech because of a water well, which Abimelech’s servants had violently taken away.

Abimelech said, “I don’t know who has done this thing. You didn’t tell me, and I didn’t hear of it until today.”

Abraham took sheep and cattle, and gave them to Abimelech. Those two made a covenant.

Abraham set seven ewe lambs of the flock by themselves.

Abimelech said to Abraham, “What do these seven ewe lambs, which you have set by themselves, mean?”

He said, “You shall take these seven ewe lambs from my hand, that it may be a witness to me, that I have dug this well.”

Therefore he called that place Beersheba, because they both swore an oath there.

So they made a covenant at Beersheba. Abimelech rose up with Phicol, the captain of his army, and they returned into the land of the Philistines.

Abraham planted a tamarisk tree in Beersheba, and there he called on the name of the LORD, the Everlasting God.

Abraham lived as a foreigner in the land of the Philistines many days.

Chapter overviewAI-generated

Overview. This chapter recounts the fulfillment of God’s promise to Abraham and Sarah through the birth of Isaac, the subsequent tension involving Hagar and Ishmael, and Abraham’s covenant with Abimelech at Beersheba. It stands at a pivotal point in Genesis, marking the beginning of the promised lineage while clarifying the distinction between the children of promise and those of the flesh, all within the larger narrative of God’s unfolding plan to bless the nations through Abraham’s seed.

Flow.

God fulfills His promise: Sarah conceives and gives birth to Isaac, and Abraham obeys God’s command by circumcising him.
Tension arises when Sarah sees Ishmael mocking and demands that Hagar and her son be cast out; God affirms Abraham’s painful decision while promising to preserve Ishmael as a nation.
God provides for Hagar and Ishmael in the wilderness, preserving their lives and confirming His earlier word.
Abraham establishes a covenant with Abimelech, securing rights to a well and naming the place Beersheba, where he worships the Everlasting God.

Connections. Following chapter 20, where Abraham’s precarious position among the Philistines is exposed through his deception about Sarah, chapter 21 shifts to a tone of promise fulfilled and divine establishment. The birth of Isaac marks a new era in the covenant, fulfilling what had long been anticipated. The tensions over inheritance anticipate the struggles in later chapters over who belongs to the line of promise, which chapter 22 will intensify in the testing of Isaac. The covenant at Beersheba prepares the way for Abraham’s enduring presence in the land, a theme pursued in the narratives that follow.

What it teaches. The chapter underscores that the covenant promises are realized not by human effort but by divine faithfulness (WCF 7.1; HC LD 23), as the birth of Isaac occurs according to God’s timing despite human frailty. Sarah’s laughter (v. 6) echoes earlier doubt but is now transformed into joy, showing God’s power to fulfill His word. The distinction between Isaac and Ishmael establishes that the covenant line is determined by God’s promise, not merely physical descent (; WCF 7.4). God’s care for Ishmael, even in expulsion, shows His mercy extends beyond the elect line (Canons of Dort I.15). The planting of the tamarisk and invocation of the LORD as El Olam (the Everlasting God) point to God’s enduring presence and faithfulness across generations (WCF 2.1).

Apply. When God establishes His promises, He secures both the heir and the provision necessary to fulfill His purpose.

AI-generated. Not a substitute for Scripture, your pastor, or the confessions.