Isaac & Ishmael: The Rightful Heir of Promise
Genesis 21
 
Genesis 21. In ch.15 the Lord promised Abraham a son from his own body. In ch.16, Abraham and Sarah seek to obtain an heir through Abraham’s union with Hagar, producing Ishmael. In ch.17 the Lord tells Abraham that he would have a son with Sarah, and his name would be Isaac. In ch.18 the Lord appeared again to Abraham and Sarah, and told them the very time when Isaac would be born! All of this was promised to faith. All the natural evidence pointed to the impossibility of Sarah having a son. Finally, in ch.21 we have the Lord bringing His word to pass. Also, in this chapter we find that the two sons, Ishmael and Isaac, could not continue in the same house, due to the way Ishmael was treating Isaac. Galatians 4 shows that the two mothers and their two sons have typical significance, having to do with law and grace, and the flesh and the Spirit. Finally, Abimelech discerns that the Lord is with Abraham, and he seeks to enter into a covenant with Abraham, to lock his family in on good terms. It speaks of the future kingdom of Christ, when all nations will align themselves with Israel, who will be the head and not the tail. 
 
 

Birth of Isaac (21:1-7)

CHAPTER 21
1 And Jehovah visited Sarah as he had said, and Jehovah did to Sarah as he had spoken. 2 And Sarah conceived, and bore Abraham a son in his old age, at the appointed time of which God had spoken to him. vv.1-2 God keeps His promise. Many years had passed, and Abraham was now “in his old age”, but finally, after all possibility of having a child through human energy was exhausted, “Jehovah visited Sarah as he had said, and Jehovah did to Sarah as he had spoken”. All this came to pass just as the Lord had promised, at the very time of year (Gen. 18:10). If we learn nothing else from this story, we should learn this: the Lord is faithful. He keeps His promises. We find in Hebrews 11 that a great change had taken place in Sarah’s soul by this time. In chapter 18 we find that she did not believe, and even laughed faith, the promise of God. But we find that her unbelief was changed to faith. “Through faith also Sara herself received strength to conceive seed, and was delivered of a child when she was past age, because she judged him faithful who had promised” (Heb 11:11). 
 
3 And Abraham called the name of his son who was born to him, whom Sarah bore to him, Isaac [‘laughter’]4 And Abraham circumcised his son Isaac, being eight days old, as God had commanded him. 5 And Abraham was a hundred years old when his son Isaac was born to him. vv.3-5 The Birth of Isaac. Abraham carries out the instructions that Lord had given in ch.17. First, he names the boy ‘Isaac’, as the Lord had said (Gen. 17:19). Isaac means ‘laughter’, and the Lord gave him that name when Abraham laughed in ch.17. His laugh there was a laugh of joy, like Sarah’s in the next verse. Abraham also followed through with the sign of the covenant, and had Isaac circumcised on the eighth day. We are given the year of Abraham’s life in which Isaac was born. This date turns out to be important in Bible chronology. We find in Genesis 12:4 that Abraham was seventy-five years old when he left Haran and came to Canaan. This means that he was in the land twenty-five years before having Isaac!
 
6 And Sarah said, God has made me laugh: all that hear will laugh with me. 7 And she said, Who would have said to Abraham, Sarah will suckle children? For I have borne him a son in his old age. vv.6-7 Sarah’s Laughter. In ch.18, when the Lord appeared to Abraham in his tent door, and He told Abraham that Sarah would have a son the following year, “Sarah laughed within herself, saying, After I am become old, shall I have pleasure, and my lord old?” It was a laugh of unbelief. There are two kinds of laughter: the laugh of joy (perhaps with surprise) and the laugh of unbelief. At that time she did not believe the promise. But now, she laughs again, and this time it is a laugh of joy! She can say “God has made me laugh: all that hear will laugh with me.” It was not a joy obtained through her own efforts, but something that God had done. It was a joy that others could enter into as well (e.g. Ruth 4:14-17). It was such an unexpected thing; “Who would have said to Abraham, Sarah will suckle children? For I have borne him a son in his old age.” But that is how God works; “For as the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts” (Isa. 55:9).
 

Dismissal of Hagar and Ishmael (21:8-21)

8 And the child grew, and was weaned. And Abraham made a great feast on the day that Isaac was weaned. 9 And Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, mocking. vv.8-9 The Mocking. When Isaac reached a certain age, he was weaned. We do not know exactly how old Isaac was at this time, but often in those days children were weaned at an much older age. Weaning is a sign of maturity. He was no longer a baby. It is interesting that this chapter is taken up in the New Testament in connection with the truth of sonship. Sonship in Christianity is the privilege believers have to be given an elevated status in the family of God. It is in connection with this privilege that Paul references that mocking of Ishmael (Gal. 4:29). The celebration of Isaac’s privileges drew forth the antagonism of Ishmael. Where did Ishmael learn to behave this way in Abraham’s house? He had learned from his mother (Gen. 16:4). Children often draw their attitude and outlook from their parents. How careful parents must be to guard their spirits, and watch what they say around the children!
 
10 And she said to Abraham, Cast out this handmaid and her son; for the son of this handmaid shall not inherit with my son — with Isaac. 11 And the thing was very grievous in Abraham’s sight because of his son. 12 And God said to Abraham, Let it not be grievous in thy sight because of the lad and because of thy handmaid: in all that Sarah hath said to thee hearken to her voice, for in Isaac shall a seed be called to thee. 13 But also the son of the handmaid will I make a nation, because he is thy seed. vv.10-12 Sarah’s Suggestion, the Lord’s Mind. Sarah knew that it was no longer possible for Hagar and Ishmael to remain in their home. She owns no responsibility toward Ishmael, although his conception was her idea. She calls him “the son of this handmaid”, but Abraham still thought of Ishmael as “his son”, for so he was. There is no way to sugarcoat this. It was a messy family situation that came to be through self-will and unbelief. The broken homes and mixed marriages of today are the result of the same thing: the flesh in action upsets God’s order in creation. Sarah’s suggestion seemed very harsh to Abraham; “the thing was very grievous in Abraham’s sight because of his son”. Yet we find that Sarah had the Lord’s mind. It was not just frustration, or pride, on Sarah’s part, but a God-given intuition. It was really human weakness on Abraham’s part. God does not call Ishmael Abraham’s son, but rather simply “the lad”. It is because in God’s sight, there was only one through whom the promised seed would come. Even though Ishmael would become a great nation, he was not the child of promise. In ch.22 we find that God says concerning Isaac, “Take now thy son, thine only son, whom thou lovest, Isaac”. Sarah had taken the lead in bringing Ishmael into the world. Abraham had not acted as the head in that situation. Now, in the government of God, he is told “in all that Sarah hath said to thee hearken to her voice”. Now he must follow her lead again, in a most painful thing.
 
Typical Significance. The events of Genesis 21 are taken up in the New Testament and shown to have typical meaning. Most notably, the dismissal of Hagar and Ishmael is explained in Galatians 4 as an allegory for the incompatibility between law and grace, and between the flesh and the Spirit. Paul explains that Hagar as a bondwoman is a type of the law. Her son is a type of the flesh that desires to be under law. Sarah as a free woman is a type of grace. Her son is a type of one who is resting on the promises of God. We find that flesh, law, and bondage are connected in one system, while Spirit, promise, grace, and freedom are connected in another. Once the child of promise was born, the bondwoman and her son were excluded. This is a powerful type of the system of the law. Once the promised Seed came, there was no more room for the law or for the flesh. Trying to mix law and grace is impossible. Also, the son of the bondwoman began to “persecute” the son of the freewoman, just the way legalism persecutes grace. The answer was to “Cast out the bondwoman and her son”. Galatians 5 explains just how we are to do that. But the events of Genesis 21 are also taken up in Romans 9. There we find v.12 quoted in support of the doctrine of sovereign election. Paul now shows that blessing in Abraham’s house did not come through natural descent, because in if blessing flowed through the paternal link, Ishmael would have been just as valid an heir as Isaac. But only one was the child of promise; “they that are the children of the flesh, these are not the children of God; but the children of the promise are reckoned as seed” (Rom. 9:7-8). He goes on to show that blessing doesn’t flow through the maternal link either, because both Jacob and Esau were sons of Rebeccah, but Jacob the younger was chosen. This shows that God blesses on the principle of His own sovereignty.
 
14 And Abraham rose up early in the morning, and took bread, and a flask of water, and gave it to Hagar, putting it on her shoulder — and the child, and sent her away. And she departed, and wandered about in the wilderness of Beer-sheba. 15 And the water was exhausted from the flask; and she cast the child under one of the shrubs, 16 and she went and sat down over against him, a bow-shot off; for she said, Let me not behold the death of the child. And she sat over against him, and lifted up her voice and wept. vv.14-16 Hagar and Ishmael Dismissed: Hagar’s Collapse. For all of his weakness and fear at times, Abraham was an obedient man. He did what the Lord commanded him, even though it was very grievous to him. He sent away Hagar and his son Ishmael. Hagar wandered in the wilderness without a sense of direction. The water ran out, and she collapsed. She acts in a very dramatic fashion, casting the child under a shrub, and sitting at a distance from him, so she would not witness his death. Then she started weeping loudly. It is hard to say for sure, but based on the way God speak to here in v.17, it seems that Hagar was being a bit dramatic. Earlier she had experienced the Lord’s care for her, and had called on the name of Jehovah as “the God who reveals Himself”. Now she seems to give up completely, without calling on the name of the Lord. Hagar is a type of Israel under the law, cast of of their land because of rejection of the heir (Isaac), and scattered among the nations. One thing they still do have is the Word of God, pictured by the by the flask of water, although they do not understand what it means. Israel today is in this position, crying out because of their circumstances, but not yet turning to the Lord in faith.
 
17 And God heard the voice of the lad. And the Angel of God called to Hagar from the heavens, and said to her, What aileth thee, Hagar? Fear not; for God hath heard the voice of the lad there, where he is. 18 Arise, take the lad, and hold him in thy hand; for I will make of him a great nation. 19 And God opened her eyes, and she saw a well of water; and she went and filled the flask with water, and gave the lad drink. vv.17-19 God Speaks to Hagar. God spoke to Hagar from heaven, and said “What aileth thee, Hagar?” It was saying to her, “What is the problem?” Perhaps this gives us a clue about Hagar’s state of soul. God encouraged her that He had heard, not Hagar’s weeping, but “the voice of the lad there, where he is”. Ishmael could not die, because God had already promised her in ch.16, and He confirms it again, that Ishmael would become a great nation. In a similar way, God has not forsaken the nation of Israel, even through they are cast out of the inheritance. They are still under a measure of God’ providential care. God opened the eyes of Hagar to see a well of water, which was sufficient to quench the boy’s thirst, and to refill the flask. 
 
20 And God was with the lad, and he grew; and he dwelt in the wilderness, and became an archer. 21 And he dwelt in the wilderness of Paran. And his mother took him a wife out of the land of Egypt. vv.20-21 The History of Ishmael. True to His word, God preserved Ishmael, and he grew, fulfilling his troubled destiny as a wilderness man. It is notable that in v.9 Hagar is referred to as “the Egyptian”, and now we find that she chose a wife for Ishmael from, of all places, Egypt. Hagar pictures the law, Ishmael the flesh, and Egypt the world. The three things go together, as we find in the epistle to the Galatians; the law, the flesh, and the world.
 

Covenant with Abimelech (21:22-34)

22 And it came to pass at that time that Abimelech, and Phichol the captain of his host, spoke to Abraham, saying, God is with thee in all that thou doest. 23 And now swear to me here by God that thou wilt not deal deceitfully with me, nor with my son, nor with my grandson. According to the kindness that I have done to thee, thou shalt do to me, and to the land in which thou sojournest. 24 And Abraham said, I will swear. vv.22-24 Abimelech Pursues a Covenant. Once Isaac was born, and Abraham had prospered in the south country for some time, a change takes place. The leader of the land in which Abraham dwelt came to him, with the general of his army, seeking a covenant with Abraham. What would cause a king like Abimelech to seek out Abraham, whom he had rebuked in the previous chapter, and establish a lasting agreement between the families? Abimelech discerned that God was with Abraham in all that he did. This Gentile king acknowledged that, somehow, Abraham and his seed would inherit that whole land. Abimelech speaks of the kindness that he had shown to Abraham, perhaps referring to Gen. 20:15. It shows the moral dignity of Abraham as the heir of the world, similar to the honor showed him by the kings in Genesis 14. It is a type of how the nations will seek out and befriend Israel in the Millennium (Zech. 8:23). 
 
25 And Abraham reproved Abimelech because of a well of water that Abimelech’s servants had violently taken away. 26 And Abimelech said, I do not know who has done this, neither hast thou told me of it, neither have I heard of it but to-day. 27 And Abraham took sheep and oxen, and gave them to Abimelech; and both of them made a covenant. 28 And Abraham set seven ewe-lambs of the flock by themselves. 29 And Abimelech said to Abraham, What mean these seven ewe-lambs, these which thou hast set by themselves? 30 And he said, That thou take the seven ewe-lambs of my hand, that they may be a witness to me that I have dug this well. vv.25-30 The Issue of Abraham’s Well. In the previous chapter, Abimelech had reproved Abraham. Now the tables are turned. There was an issue with a well Abraham had dug. Abimelech’s servants had violently seized the well, and it was something Abraham brought up to Abimelech. So it will be in the Millennium, that the Gentiles will not be permitted to trespass against the restored Jews. Israel will be, as God intended them, “the head, and not the tail” (Deut. 28:13). Abraham gave sheep and oxen to Abimelech to seal the covenant, and set “set seven ewe-lambs of the flock by themselves”. At the king’s request, Abraham explained that the lambs were to be a witness that the well belonged to Abraham. Perhaps Abraham had a sense that there was something in these Philistines that envied his success, and wanted to take what they had not worked for. This turned out to be right, because in the days of Isaac, we read that the Philistines envied him because of his wealth, and that they had filled “all the wells” which Abraham had dug with earth (Gen. 26:14-15).
 
31 Therefore he called that place Beer-sheba [‘well of the oath’], because there they had sworn, both of them. 32 And they made a covenant at Beer-sheba. And Abimelech rose up, and Phichol the captain of his host, and returned into the land of the Philistines. 33 And Abraham planted a tamarisk in Beer-sheba, and called there on the name of Jehovah, the Eternal GOD. 34 And Abraham sojourned in the Philistines’ land many days. vv.31-34 The Covenant at Beer-sheba: Abraham’s Orchard. The place were Abraham and Abimelech made their covenant was called Beer-shebe, which means ‘well of the oath’. This place became the southern border of the land of Israel, in a similar way to how the city of Dan marked the northern border. This is why we have the expression often in the Old Testament, “all Israel, from Dan even to Beer-sheba” (1 Sam. 3:20). Abraham planted a tamarisk, or a large tree (possibly a grove or orchard of trees) in this place, to mark the border. The orchard may also be a type of the fruitfulness of the earth in the Millennium. Abraham’s sojourning for “many days” in the land of the Philistine may also be a type of the thousand years of the Messiah’s reign over all nations. Then he “called there on the name of Jehovah, the Eternal GOD”, as a witness that this land would belong to his family for ever. What praise and thanksgiving must have flowed from Abraham’s heart in response to God’s faithfulness in keeping His promise; Abraham had a son, an heir, and the land secured to his family. He had it all! This concludes the second series of chapters in the life of Abraham, which began with ch.15. The next chapter begins a fresh departure in God’s ways.
 
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