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July 2, 2024

Genesis Part 21

The last piece of information that Abraham received from God in Genesis Chapter 15 regarding the covenant promise was that his wife, Sarah, would bear a son, and the son’s name would be Isaac.




GENESIS 21:1-13

The last piece of information that Abraham received from God in Genesis Chapter 15 regarding the covenant promise was that his wife, Sarah, would bear a son, and the son’s name would be Isaac. It is through Isaac and not Ishmael that God would establish His covenant to be a great nation with a land to possess, and through whom the nations of the world would be blessed. This is reiterated in Genesis 18:10: “This time next year your wife Sarah will have a son!” So then, Abraham is informed that in one year the child of promise, Isaac, will be born.

One year later…

READ Genesis 21:1-3

“The LORD visited Sarah” indicates that God comes to Sarah with supernatural power and gives her the ability to conceive at the age of 90! Notice the emphasis in this verse – “as HE had said” and “as HE had promised.” God does for Sarah what He said He would do in Genesis Chapter 17. And God does it in the timeframe that He had said – “at the time of which God had spoken” (Genesis 18:10). Abraham responds in obedience by naming his son Isaac as God had directed.

READ Genesis 21:4-5

Abraham circumcises Isaac when he is 8 days old. This is obedience to God’s instruction in Genesis 17:12. The fact given that Abraham is 100 years old confirms that God kept His promise to Abraham in the timeframe He told him. Abraham was 99 when God told him that Sarah would conceive and Isaac would be born (17:24). Shortly thereafter, in Genesis 18:10, God tells Abraham it will happen this time next year. One year has passed and now we see that Abraham is 100. So, Isaac’s birth happened exactly as God said it would and when it would.

READ Gen 21:6-8

Sarah’s laughter back in Genesis Chapter 18, which was a laughter of unbelief, is now laughter of pure unbridled joy. And she shares that laughter with others around her. “Who would have said to Abraham that Sarah would nurse children?” Only one Person would have said that and it was God. Weaning is the discontinuation of breast-feeding. It is when a child begins to get their nourishment from solid food. In some cases this could extend to a child’s 2nd or 3rd birthdays. Isaac is probably around a year old, maybe 2, at this time. So Ishmael, Abraham’s first son, would have been 15 or 16 years old.

At this point the focus is on the covenant child Isaac. He is the center of attention. It is not just that Isaac is Abraham’s and Sarah’s miracle child, though he certainly is. The main point of emphasis is that Isaac is the one through whom God’s promises to Abraham will be fulfilled. The Abrahamic Covenant hinges on Isaac. Abraham knows this. This is a vitally important point to grasp because in next week’s lesson Abraham is going to be tested on this point to see if he really does get it. So before we even get to that lesson I want you to understand something – Abraham knows that Isaac is the child of promise and all of God’s promises to him are going to be fulfilled through Isaac and not Ishmael. God has made this crystal clear to Abraham. It is my contention that not only does Abraham believe this, but he KNOWS IT!!

READ Gen 21:9-11

Notice that Ishmael is not even mentioned by name in these verses. He is merely called “the son of Hagar” or “the son of this slave woman” or “his son.” There is a literary point in play here. Moses, writing this under the inspiration of the Holy Spirit, downplays Ishmael while, at the same time, he emphasizes Isaac. Ishmael was last mentioned by name in Genesis 17:26 and will not be mentioned again until Genesis 25:9. Meanwhile Isaac is mentioned by name 21 times during that span.

 The ESV uses the word “laughing” to describe what Ishmael is doing. But his laughter is being done in a jesting or mocking sense. He is belittling Isaac. There is more going on here than just some teenager mocking, teasing or picking on his baby brother. And Sarah sees it. Ishmael poses a serious threat to Isaac. He’s mocking the promised seed, a one or two year old boy now – there is no telling what he might do later! Well, God uses this incident as the catalyst to drive out Ishmael and Hagar. He removes the threat. Naturally, Abraham, who loves his son Ishmael very much, does not like Sarah’s suggestion to “cast out” Hagar and her son.

READ Genesis 21:12-13

But God directs Abraham to do what Sarah suggested and here’s why: “for through Isaac shall your offspring be named.” Isaac is the child of promise, not Ishmael. The name of the great nation that God will make of Abraham comes through Isaac. He will have a son named Jacob and God will change his name to Israel. And that is the name God will use for his covenant nation. God knows all this already. God goes on to reassure Abraham that He will take care of Ishmael and make him a great nation.

And so as we read the rest of the chapter Abraham does as God directs and the next morning sends Hagar and Ishmael away with food and water. God provides for them in the Desert of Beersheba. God allows Hagar to see a well of water, possibly one of the wells that Abraham had dug, and from that they were able to survive. We read later in the genealogy of Ishmael in Genesis Chapter 25 that he had 12 sons. This is what God had predicted in Genesis 17:20. Ishmael lives to the age of 137. At this point Ishmael fades from the scene and Isaac slowly becomes the focal point of the story.

In Galatians 4:28-30 Paul uses this story to drive home a spiritual point: “Now you, brothers, like Isaac, are children of promise. But just as at that time he who was born according to the flesh persecuted him who was born according to the Spirit, so also it is now. But what does the Scripture say? ‘Cast out the slave woman and her son, for the son of the slave woman shall not inherit with the son of the free woman.’ So, brothers, we are not children of the slave but of the free woman.”


Our God does what He says He will do – He does it in His time, in His way and in the people He chooses. He may include us in His plan and He listens to our prayers. But He doesn’t need our help nor our advice. What He desires from us is our faithful obedience to Him and His word.

GENESIS 21:1-13

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