Chapter 21
Sarah has Isaac when Abraham is 100 years old. So she was 90. All the things in Chapter 20 happened in the year between when the three visited Abraham prior to the destruction of Sodom and Gomorrah and the time Isaac was born. There is a note in MSB which implies that Abraham and Sarah had been married for 25 years when Isaac was born. Isaac means "he laughs". Ishmael meant "God hears".
2021 - There is no "Abraham went in to Sarah" or anything like that in this chapter. Rather, it says the Lord visited Sarah as he had promised. So is this a reference to her being able to get pregnant in her old age, or is the return visit promised by at least one of the three visitors from a year before. So...when exactly did she get pregnant? She had been in the house of Abimelech for some time. Was she pregnant already when she went there? Which would mean she went in there a month or so after the visit by the three men, and she would have been showing, though 90 years old, while in that house, and Abimelech would know he wasn't responsible. This would likely have started inquiries even before the dream that Abimelech had. As nearly as we can tell, Abraham was still on the move when Isaac was born. They were in Gerar, but had not settled anywhere yet - or at least we haven't been told about it yet. Note that vs 2 says "And Sarah conceived..." and implies that she didn't get pregnant until after they had left Abimelech's house. Here s the wording of the "one year promise": 10 The LORD said, "I will surely return to you about this time next year, and Sarah your wife shall have a son." And Sarah was listening at the tent door behind him. [Gen 18:10 ESV] So it does not say precisely one year. It does not say the son will be born in a year. The one speaking - whom the translators have interpreted as being Jehovah - will come back in a year, and she will have a son. So there is room for two years in here without violating what any of the verses actually say. In fact, the promise of a return visit, which I though we were never told about, is confirmed in vs. 21:1, in no uncertain terms.
2021 - Look at this wording: 3 Abraham called the name of his son who was born to him, whom Sarah bore him, Isaac. [Gen 21:3 ESV] The FACT that Isaac is Abraham's son is reinforced three times in this verse, like a hammer driving home a nail, emphasizing that God was keeping a very large promise, and that he was doing miracles and setting aside the natural order and way of things to make it happen. Even more interestingly, this is Sarah's first, and only child.
2023 - I cannot help but notice the similarity between the way Isaac's conception is described and that of Jesus. There just aren't many differences. Angel's announce both, there is no "knowing" described, God is said to do as he said he would do...and we need to remember that Isaac would be laid out as a sacrifice not all that long after he is born, by his own father. Surely there is a lot of typology here. But there are also limits on it. Sarah's experience after Isaac is born is completely different than Mary's. But the two stories still have much in common. Both are miraculous, in that one birth is to a 90 year old and the other to a virgin. But there is never any implication that Sarah is a virgin. There is vs. 16, which seems to be about averting any suspicion that Abimelech had slept with Sarah: 16 To Sarah he said, "Behold, I have given your brother a thousand pieces of silver. It is a sign of your innocence in the eyes of all who are with you, and before everyone you are vindicated." [Gen 20:16 ESV], just as Joseph was told by an angel not to worry that there was a human father of Mary's baby.
When Isaac is weaned, Abraham has a celebration. Sarah sees Ishmael laughing. She gets really angry. Ishmael would have been older by this time, 13 or 14 - and he could well have known that as Abraham's first born, he would inherit the greater share, and was laughing at Isaac because of this. Hagar probably had more than a little to do with his attitude, telling him the story of how he was going to be a great nation. In their minds, they probably saw this coming about as Ishmael being the heir of Abraham, and so getting the lions share of everything. I expect it was Hagar's attitude that got her into trouble back in the Beer-lahai-roi days, and now she's passed that attitude to her son. Plus, we know that Ishmael will be a "donkey of a man". Heck of a worker, not very smart, stubborn to his own harm. We see the beginning of that also in these verses. Sarah asks Abraham to sort of banish Ismael and Hagar to insure that Ishmael will not get any inheritance at all. Abraham is not at all pleased by this request. Yet God tells him to do it, He will take care of the details.
And I will make a nation of the son of the slave woman also, because he is your offspring."
Genesis 21:13 ESV
God's promises are true, even when we mess them up by helping.
Abraham sends Hagar and Ishmael off with very little in the way of provision or survival possibilities. Only one skin of water goes with her. He sends no slaves with her, no man, no protection, possibly not even a camel to ride on. She wanders around in Beersheba.
And God heard the voice of the boy, and the angel of God called to Hagar from heaven and said to her, "What troubles you, Hagar? Fear not, for God has heard the voice of the boy where he is.
Genesis 21:17 ESV
The boy, not Hagar.
And God was with the boy, and he grew up. He lived in the wilderness and became an expert with the bow. He lived in the wilderness of Paran, and his mother took a wife for him from the land of Egypt.
Genesis 21:20-21 ESV So Ishmael is half Egyptian, and his children will be 3/4's Egyptian. Not much Hebrew in him at all, yet God blesses him as Abraham's son.
Abraham consents to an alliance with Abimelech and with Phicol his military commander, to deal honestly with them at all times because of the generosity that Abimelech has shown Abraham. This verse: 31 Therefore that place was called Beersheba, because there both of them swore an oath. [Gen 21:3, 31 ESV]. So here is the origin of this place name that we will see so many more times in the Bible.
It says in vs 32 that Abimelech returns to the land of the Philistines. So this is where Abraham had been living.
2026 - Yehova, olam el. The LORD, the everlasting God.