Lesson 18: Genesis 21

The Hebrew author urged Christians to “Let us hold fast the confession of our hope without wavering, for he who promised is faithful.” (Hebrews 10:23, ESV) The story of the Bible is the story of God being faithful to His promises and Genesis 21 stands as testimony not only to God’s promises to Abraham (Genesis 12.1-3), but also to His promise to redeem mankind (Genesis 3.15).

Twenty five years had passed since the Lord called Abraham, promising to make of him a great nation. Abraham and Sarah’s faith had been challenged to fully trust in the Lord, believing that nothing was “too hard for the Lord” (Genesis 18.14). Both struggled at times, yet they remained firm in their faith that “God was able to do what he had promised” (Romans 4.21). The Scriptures make it clear that it was the Lord who gave Abraham the promised heir, not any effort of man. And if the Lord had been faithful to give Abraham his heir, He would also be faithful to bless “all families of the earth”.

Notes From The Text:

Vss. 1-7, Birth of Isaac

• Vss. 1-2
  • For all of the buildup to the buildup to the birth of Isaac, not much is said about his actual birth. But what is said is essential: it was the Lord who “visited Sarah” and who did “as he had promised.”
  • Note 1Samuel 2.21, the Lord also “visited” Hannah. The child was Abraham’s (Genesis 17.19; Romans 4.19-21), but the language of the text is emphasizing that Isaac’s birth was possible only because of the Lord.
  • “at the time of which God had spoken to him” see Genesis 18.10.
• Vs. 3, see Genesis 17.19.
• Vs. 4, see Genesis 17.10.
• Vs. 6, recall that both Abraham and Sarah had laughed (Genesis 17.17; 18.12). While Sarah’s laugh seem to have been one of doubt, the naming of Isaac (lit. “he laughs”) now contains only joy for Sarah.

Vss. 8-21, Ishmael & Hagar Sent Away

• Vs. 8, a child was usually weaned at the age of three. When Isaac was three, Ishmael would have been seventeen.
• Vs. 9, the ESV’s translation of “laughter” is not as strong as it could be. The NASB and NIV get closer to the idea with “mocking”. It was so severe that Paul described Ishmael’s treatment of Isaac as persecution (see Galatians 4.29).
• Vs. 10
  • Sarah’s words may help us to understand how exactly Ishmael was mocking or persecuting Isaac. Ishmael, as the older son of Abraham, may very well have seen himself as the legitimate heir. Thus, Ishmael’s mocking would have been boasting of his own exalted status in the family. Sarah’s concern was warranted, because the son of flesh (Ishmael) was not to be heir with the son of promise (Genesis 17.15-19; see Galatians 4.30).
  • Recall that Hagar had been Sarah’s handmaiden (Genesis 16.1). However, she had been given to Abraham as a wife (Genesis 16.3). Thus, Sarah could not “cast out” Hagar without Abraham agreeing to do so. Significantly, the Hebrew word for “cast out” in vs. 10 is translated “divorced” in Leviticus 21.7,14; etc. and the term translated as “sent her away” in vs. 14 is the verb for “divorce” in Malachi 2.16. Hagar had to be divorced so that her son, Ishmael, could have no claim to the inheritance.
• Vs. 11, recall that Abraham had earlier expressed concern over Ishmael’s standing (Genesis 17.18). While Sarah’s son would be the heir, the Lord had promised to bless Ishmael (Genesis 17.20).
• Vs. 12, the significance of this verse is fully revealed in the next chapter. Isaac is the son of promise, not Ishmael. And if all depends on Isaac, then certainly he must live…
• Vs. 13, see Genesis 17.20.
• Vs. 14, note that Abraham did not hesitate to obey the Lord’s command (see also Genesis 22.3). Note also that Hagar did not journey back toward Egypt has she previously had done (Genesis 16.7).
• Vs. 15, the language paints a sad picture. Ishmael, a boy of seventeen, is so week at this point that his mother has to help him settle underneath the bushes.
• Vs. 16, “This scene of Hagar’s grief was compounded by a combination of physical need and of discouragement. Even though the region south of Beersheba is very dry during most of the year, it is possible to find water, if one knows where. But think of Hagar’s position. For years now she had lived comfortably within Abraham’s household, and she had even given her master a son. Ever since his birth it had been understood that her son would inherit all the vast wealth of Abraham—until this new child Isaac was born. Even after Isaac’s birth, Hagar and Ishmael would have assumed that he would still inherit a large portion of Abraham’s wealth. Now they are sent away as if in disgrace. Their bottle of water was empty, and they had not found water in this barren region—and they were deeply discouraged.” (Bob Waldron)
• Vs. 17, note that it was the boy’s voice that the Lord heard. Recall that Ishmael’s name means “God hears” (Genesis 16.11).
• 

Before we move on from this section, we must return to Paul’s argument in Galatians 4. Recall that he had likened Judaism (those relying on circumcision and the Law) to the children of the slave woman Hagar, while those who put their faith in Christ are children of the free woman (vss. 21-27). Thus, Christians are like Isaac in that we are the children of promise (vs. 28). And what of the children of the slave woman? They persecute the children of the free woman (29) and they must be cast out; they cannot inherit the promises with the children of faith (vs. 30). The point: the only way to inherit the promises and blessings of God is through faith in Christ. Any other attempt is the doing of man, and not God; any other attempt can only result in slavery and being cast out.

Vss. 22-34, Treaty with Abimelech

• Vss. 23-24, recall that Abimelech had previously tried to enter into an alliance with Abraham through marriage (Genesis 20.2). That was unsuccessful, but the king still wished to have an alliance with Abraham, whom he saw as a powerful chieftain.
• Vss. 25-26, Abraham is willing to enter the alliance, but he has a complaint that must first be addressed. The difficulty of finding and securing water was so difficult in the southern part of Canaan, that the seizing of a well would have been a great act of hostility. Abimelech’s claim of innocence may not have been sincere (see Genesis 26).
• Vs. 27, these animals would have been slain as part of the covenant making process (see Genesis 15.9-10,17-18).
• Vs. 31, Beersheba means “well of the oath” or “well of the seven”.
• Vs. 33, “ēl ‘ôlām, the Everlasting God,… a logical epithet of a Deity called upon to support a formal treaty … expected to be valid for all time.” (Derek Kidner)
• Vs. 34, “At this point, for the first time, the region of Gerar is identified as the land of the Philistines. While the main force of Philistines would not invade the region until about 1200 B.C., a sizable enclave of this people seems to have settled in the southern coastal plain at a very early age (Gn 26; Ex 13:17).” (James E. Smith)