CHAPTER 21 Jan. 11 
The Birth of Isaac 
Yahweh visited Sarah as He had said, and Yahweh did to Sarah as He had spoken. 2Sarah conceived, and bore Abraham a son in his old age, at the set time of which God had spoken to him. 3Abraham called his son who was born to him, whom Sarah bore to him, Isaac. 4Abraham circumcised his son Isaac when he was eight days old, as God had commanded him. 5Abraham was one hundred years old when his son Isaac was born to him. 6Sarah said, God has made me laugh. Everyone who hears will laugh with me. 7She said, Who would have said to Abraham, that Sarah would nurse children! For I have borne him a son in his old age.
Hagar Is Thrown Out 
8The child grew, and was weaned, and Abraham made a great feast on the day that Isaac was weaned. 9Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, mocking. 10Therefore she said to Abraham, Cast out this handmaid and her son! For the son of this handmaid will not be heir with my son Isaac! 11The thing was very grievous in Abraham’s sight on account of his son. 12God said to Abraham, Don’t let it be grievous in your sight because of the boy, and because of your handmaid. In all that Sarah says to you, listen to her voice. For in Isaac will your seed be called. 13I will also make a nation of the son of the handmaid, because he is your seed. 14Abraham rose up early in the morning, and took bread and a bottle 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. 15The water in the bottle was spent, and she cast the child under one of the bushes. 16She went and sat down opposite him, a good way off, about a bow shot away. For she said, Let me not see the death of the child. She sat over against him, and lifted up her voice, and wept. 17God heard the voice of the boy. The angel of God called to Hagar out of the sky, and said to her, What ails you, Hagar? Don’t be afraid. For God has heard the voice of the boy where he is. 18Get up, lift up the boy, and hold him in your arm. For I will make him a great nation. 19God opened her eyes, and she saw a well of water. She went, filled the bottle with water, and gave the boy drink. 20God was with the boy, and he grew. He lived in the wilderness, and as he grew up he became an archer. 21He lived in the wilderness of Paran. His mother took a wife for him out of the land of Egypt.
The Argument about Beersheba 
22It happened at that time, that Abimelech and Phicol the captain of his army spoke to Abraham, saying, God is with you in all that you do. 23Now 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. 24Abraham said, I will swear. 25Abraham reproved Abimelech because of a water well, which Abimelech’s servants had violently taken away. 26Abimelech said, I don’t know who has done this thing. You didn’t tell me, neither did I hear of it, until today. 27Abraham took sheep and cattle, and gave them to Abimelech. Those two made a covenant. 28Abraham set seven ewe lambs of the flock by themselves. 29Abimelech said to Abraham, What mean these seven ewe lambs which you have set by themselves? 30He 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. 31Therefore he called that place Beersheba, because they both swore there. 32So 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. 33Abraham planted a tamarisk tree in Beersheba, and called there on the name of Yahweh, the Everlasting God. 34Abraham lived as a foreigner in the land of the Philistines many days.

Commentary

21:10 Her attitude in implying that Ishmael was not the seed is gently rebuked by God in his subsequent words to Abraham concerning Ishmael: “He is your seed” (Gen. 21:13). And yet Sarah's words are quoted in Gal. 4:30 as inspired Scripture! Here we see the wonder of the God with whom we deal, in the way in which He patiently bore with Sarah and Abraham. He saw through her anger, her jealousy, the pent up bitterness of a lifetime, and he saw her faith. And he worked through that screaming, angry woman to be His prophet. According to Gal. 4:30, God Himself spoke through her in those words, outlining a principle which has been true over the generations; that the son of the slave must be cast out, and that there must always be conflict between him and the true seed. Sarah in her time of child-birth is likened to us all as we enter the Kingdom, full of joy (Is. 54:1-4); and yet at that time she was eaten up with pride and joy that she could now triumph over her rival. And yet Sarah at that time is seen from a righteous perspective, in that she is a type of us as we enter the Kingdom. God's gracious counting of righteousness to Sarah and Abraham is repeated to us daily.
21:34 Lived as a foreigner- alluded to in Heb. 11:9, which says that Abraham lived in the promised land as a foreigner. He is our example and spiritual father. His characteristics are to be seen in us who have been baptized into Christ and thus become Abraham’s seed (Gal. 3:27-29). Although this earth where we live has been promised to us, it’s our eternal inheritance which we will receive at Christ’s return, yet we now live in our own land as if we’re foreigners.