Genesis Lesson 21 | 21:1–21:34

Prayerfully read Genesis 21 at least two times and then read the following notes.

Context: Setting the Table

After a creational prologue, Genesis divides into two unequal halves of five sections each. The first half of the book (2:4–11:26) deals with the history of humanity as a whole, from its creation to the birth of Abram. The second half of the book (11:27–50:26) focuses on the history of the patriarchs. In these ninth and tenth installments of the story of Abraham, Sarah gives birth to Isaac, Ishmael is sent away, and Abimelech makes a covenant with Abraham.

Content: Reading the Text

Introductory Note
While verses 1–21 relate several incidents, they form a single cohesive section. The story of Abimelech’s covenant of Abraham, while certainly connected to its context, forms a separate section.
(21:1–7) The Birth of Isaac
(21:1) The double statement “as he had said/as he had spoken” places heavy emphasis on the precise fulfillment of the word of the Lord. He did exactly what he said he would do all along.
(21:2) The Hebrew word translated as “the set time” is the exact word used by the Lord in Genesis 17:21 and 18:14. Despite the doubts and anxieties of Abraham and Sarah, God was not a single day late in the fulfillment of his promises.
(21:3) In naming his son Isaac, Abraham obeyed the command found in Genesis 17:19. The name Isaac is identical with the verb used to describe Abraham’s laughter in Genesis 17:17. Not surprisingly, chapter 21 contains a large number of word-plays on Isaac’s name. It is striking that Isaac, divinely named before his birth, “is the only patriarch who does not undergo a change of name.”1
(21:4) Having obeyed God by naming his son Isaac, Abraham continued to obey by circumcising him on the eighth day. As Abraham had been circumcised in his old age and Ishmael as a young teenager (Genesis 17:25–26), Isaac was the very first to be circumcised in accordance with the details of the divine command regarding circumcision (Genesis 17:12).
(21:5) Abraham had been 75 years old when God first promised him abundant descendants (Genesis 12:2, 4). He had now been waiting a full quarter-century when God miraculously fulfilled his promises—to the letter.
(21:6) As earlier mentioned, these references to laughter are word plays on the name of Isaac. As Sarah had earlier laughed at the seeming impossibility of God’s promises so now she laughs in her joy at their fulfillment.
(21:7) While Sarah’s reference to nursing “children” is somewhat ambiguous, the sense is most likely something along the lines of, “who would have said that Sarah would become a nursing mother?” In Hebrew, plural forms can sometime be used to indicate “kind” or “species,” and this seems to be the case here.2
(21:8–21) The Expulsion of Ishmael
(21:8) “Breast-feeding in traditional societies often continues much longer than in the West, so that a child may not be weaned until he is three.”3 As Ishmael was already 13 (Genesis 17:25) before Isaac was even conceived, he was likely at least 16 by the time Isaac was weaned.
(21:9) Though the text does not make explicit exactly what Ishmael was up to, a few points are helpful. (1) The word translated as “mocking” is another form of the word earlier translated as “laughter” (21:6), which of course is itself a form of Isaac’s name. (2) We should therefore see some sort of connection between the joyous laughter occasioned by Isaac’s birth and whatever it was that Ishmael was doing. As Calvin points out, both were, though in very different ways, sons of laughter.4 (3) However, the particular grammatical form5 used here, is elsewhere always found in contexts that imply scornful mockery (Judges 16:25), sexual activity (Genesis 26:8) or both (Genesis 39:14). It is never merely innocent laughter—and this seems to be what Paul picks up on when he describes Ishmael’s activity as a “persecution” of Isaac (Galatians 4:29).
(21:10) Though Sarah’s response may seem to us unduly harsh—and though she herself may have been partly driven by selfishness and jealousy—it was nonetheless in accordance with God’s word (Genesis 15:3; 17:21). No matter what Abraham may have wanted, Isaac and Ishmael could never be co-heirs in the covenant promises of God.
(21:12) The very vindictiveness of Sarah’s anger (and the memory of her previous bad advice in chapter 16) initially leads the reader to expect that God is going to side with Abraham—yet he doesn’t. Though Abraham’s affection for his first-born son was entirely understandable, the continued presence of Ishmael in his household formed an obstacle to the fulfillment of God’s purposes that had to be removed. While God is always just, we must understand that he is by no means bound to do or command only that which seems “fair” to us.
(21:14) Though it leads to considerable grammatical awkwardness, the handing over of “the child” is saved for the very end of the description of Abraham’s preparations for Hagar’s departure. This “delay in mentioning the transfer of Ishmael implies Abraham waited till the last possible minute.”6 Though Ishmael was not the son of promise, he was very dear to his father—and now he had to be sent away. When the pain of waiting for God to fulfill his promises seems most unbearable, we need to consider the far greater pain of failing to wait.
(21:17) Though Hagar was crying, it was the voice of Ishmael (whose name means God hears [Genesis 16:11]) to which God listened. “His behavior led to their expulsion and his prayer to their salvation.”7
(21:19) Note the parallel with Genesis 22:13. Though Isaac was the one God had chosen to fulfill his purposes, this did not mean that he would lead an un-threatened existence! Being chosen by God is about the fulfillment of his purposes, not the maximizing of our comfort and sense of security.
(21:22–34) Abimelech Makes a Covenant with Abraham
(21:22a) The Hebrew phrase translated as “at that time” elsewhere occurs only in Genesis 38:1. In both of these cases, it seems to introduce something parenthetical to the main storyline. Given that Hagar is already wandering in the wilderness of “Beer-sheba” in verse 14 (see verse 31), it seems likely that this account took place at some point between the birth of Isaac and the expulsion of Ishmael.
(21:22b) This story is constructed in quite an artful way. “Each of the names of the two principal characters, Abraham and Abimelech, occurs exactly seven times.”8 As normal grammar would demand the use of Abraham’s name in verse 33 (it is supplied in all standard English translations), this is clearly intentional. Even more strikingly, the word translated as “oath” uses the same letters in Hebrew as the word for the number seven—note also the seven ewe lambs in verse 28.
(21:23) Given the shameful way he had so recently treated him, Abimelech’s concerns about the possibility of Abraham deceiving him in the future were entirely understandable!
(21:26) The portrayal of Abimelech matches perfectly with that given in chapter 20. In both, he starts out sounding quite noble (his protestations of righteousness/his concern for Abraham to tell the truth to Abimelech’s heirs) and ends up looking rather hapless (he was only restrained from Sarah by his own impotence/he didn’t even know what his servants were up to in the present).
(21:32) The Philistines that threatened Israel from the time of Samson onward were part of the wave of “sea peoples” that attacked Egypt and settled in Canaan around 1200 BC—several hundred years after the time of Abraham. Yet it is not necessary to see the references to Philistines in Genesis as an “anachronism,” much less as an error. “Unlike the depiction of the Philistines in Judges and Kings, these of the patriarchal period do not inhabit the Shephelah but are situated inland in the south. There is no pentapolis [the five cities of the later Philistines—1 Samuel 6:4] with [‘lords’] but a king of a single city who acts alone….the “Philistines” of patriarchal times may have belonged to a much earlier, minor wave of Aegean invaders who founded a small city-state in Gerar long before the large-scale invasions of the Levant, which led to the occupation of the Canaanite coast.”9

Credo: Believing the Truth

For a quarter of a century Abraham waited. His clumsy attempts to bring God’s promises to fruition had complicated his life immensely without furthering God’s purposes in the least. Yet while Abraham sometimes seemed to forget about God, God never forgot about Abraham. In his own perfect time, Sarah gave birth to Isaac—the son that God had promised all along. Though Abraham’s past failures had ongoing consequences, they were utterly powerless to thwart the perfect fulfillment of God’s promises.

Conduct: Reshaping Our Walk

Discuss the meaning of the text and then walk through the following application questions as you discuss the difference this meaning ought to make in our lives today.
Despite their doubts, God’s fulfillment of his promises to Abraham and Sarah was perfect in every way. How might we be tempted to forget that God always keeps his word?

Examples: Turning our back on Jesus because we feel that we have been “let down” by God; Allowing a cynical spirit to cloud our own and others joy in the wonderful promises of God; etc.

God’s promises to Isaac demanded that Abraham, despite his great affection for Ishmael, cast out his firstborn son. What are some of the ways in which our own natural affections could tempt us to ignore the difficult decisions God calls us to make?

Examples: Singles who are unwilling to end toxic relationships that are harming both parties; Refusing to give up traditions or habits that hinder God’s purposes in our own or others lives; etc.

1. Sarna 1989, 145
2. Sarna 1989, 146
3. Wenham 1994, 81
4. Calvin 1847 1.542
5. That is, the piel stem, several forms of which are used
6. Wenham 1994, 78
7. Wenham 1994, 85
8. Sarna 1989, 148
9. Sarna 1989, 390