Bible Commentaries
Genesis 21

Dr. Constable's Expository NotesConstable's Expository Notes

Verses 1-7

God’s provision and Abraham and Sarah’s response 21:1-7

The emphasis in this brief section is on the faithfulness and power of God in keeping His promise and providing an heir miraculously through Sarah (Genesis 17:16; Genesis 18:14). Note the threefold repetition of "as He had said," "as He had promised," and "of which God had spoken" (Genesis 21:1-2). The tension of anticipation finally subsides, but only temporarily.

God "visited" Sarah (Genesis 21:1, NIV), a common metaphor that describes God’s intervention in nature and human afffairs. The Hebrew word translated "visited" (paqad) also appears when God intervened to save the Israelites from Egyptian bondage (Genesis 50:24-25; Exodus 4:31) and when He ended a famine (Ruth 1:6). It also occurs when He made Hannah conceive (1 Samuel 2:21) and when He brought the Jewish exiles home from Babylonian captivity (Jeremiah 29:10). Thus its presence here highlights the major significance of Isaac’s birth.

Abraham’s obedience in naming his son "Isaac" (Genesis 17:19) and circumcising him on the eighth day (Genesis 17:12) was an expression of worship.

Isaac’s name ("laughter") was appropriate for two reasons.

1. Isaac would be a source of joy to his parents as the fulfillment of God’s promised seed.

2. Both Abraham and Sarah had laughed in amazement and unbelief respectively when told that God had chosen to bless them by giving them a son so late in life (Genesis 17:17; Genesis 18:12). [Note: On the alternate reading of Genesis 21:6-7 as "God has made a joke of me . . . laugh at me . . .," see Isaac Rabinowitz, "Sarah’s Wish (Gen. XXI 6-7)," Vetus Testamentum 29 (July 1979):362-63. This reading has not won support from most commentators.]

Verses 1-21

12. The birth of Isaac 21:1-21

God proved faithful to His promise by providing Isaac. Abraham and Sarah responded with obedience and praise. Ishmael, however, became a threat to Abraham’s heir and, consequently, his father sent him away into the wilderness where God continued to provide for him and his mother.

Verses 8-21

The expulsion of Ishmael and God’s care of him and Hagar 21:8-21

All was not well in Abraham’s household even though God had provided the heir. Ishmael was a potential rival to Isaac’s inheritance. This section records another crisis in the story of Abraham’s heir. Waltke pointed out six parallels between Hagar and Ishmael’s trek and Abraham and Isaac’s (ch. 22). [Note: Waltke, Genesis, p. 292.]

Normally in ancient Near Eastern culture the son of a concubine became the heir of his mother but not of his father (cf. Judges 9:1-3). Now that Abraham had a son by his wife, Sarah did not want Ishmael to share Isaac’s inheritance. Weaning would have normally occurred at age two or three (cf. 1 Samuel 1:22-24; Hosea 1:8). The Hebrew word translated "mocking" (Genesis 21:9) comes from the same root as Isaac’s name and means "laughing." However this participle is in the intensive form in Hebrew indicating that Ishmael was not simply laughing but ridiculing Isaac (cf. Galatians 4:29). Ishmael disdained Isaac as Hagar had despised Sarai (Genesis 16:4). Abraham understandably felt distressed by this situation since he loved Ishmael as well as Isaac (cf. Genesis 17:18). God appeared to him again (the seventh revelation) to assure Abraham that Sarah’s desire was in harmony with His will (cf. Genesis 17:19-21). He encouraged Abraham to divorce Hagar.

"But how could God ask Abraham to do evil if divorce is always a sin? The answer must be that divorce in this case is either not a sin or else is the lesser of two evils." [Note: Joe M. Sprinkle, "Old Testament Perspectives on Divorce and Remarriage," Journal of the Evangelical Theological Society 40:4 (December 1997):535.]

For other instances where God apparently commanded divorce, see Deuteronomy 21:10-14 and Ezra 9-10. Since God makes the rules, He can also alter them according to His sovereign will.

"The key to Sarah’s demand lies in a clause in the laws of Lipit-Ishtar where it is stipulated that the father may grant freedom to the slave woman and the children she has borne him, in which case they forfeit their share of the paternal property." [Note: Sarna, Understanding Genesis, p. 147.]

The laws of Lipit-Ishtar were laws that governed life in Mesopotamia that antedated the Mosaic Law.

The focus of this revelation is a clarification of God’s purposes for each of the two sons. God would bless Abraham through Ishmael as well as through Isaac.

"As Cain suffered both banishment from the divine and protection by the divine, so Ishmael is both loser and winner, cut off from what should be his but promised a significant lineage." [Note: Hamilton, The Book . . . Chapters 18-50, p. 81.]

The concluding description of Ishmael’s experiences (Genesis 21:14-21) provides information essential to understanding and appreciating later references to him and his descendants in the text. Ishmael became the father of 12 sons (Genesis 25:13-16) as Jacob did. From his sons came the Arab nations that have ever since been the chief antagonists of the Israelites. The term "Arab" (someone from Arabia) came into use for the first time in the ninth century B.C. [Note: Wenham, Genesis 16-50, p. 156.] Hagar chose a wife for her son from her homeland, Egypt.

"In this respect she does not display the wisdom used by Abraham in choosing, as he did, a god-fearing wife for his son." [Note: Leupold, 2:609.]

"The picture of Ishmael as the rejected son is complete: he is the son of a slave woman, married to an Egyptian, lives outside normal social bounds, and is remembered for his hostilities." [Note: Mathews, Genesis 11:27-50:26, p. 274.]

God not only makes promises but also provision. His provision of what He has promised results in great joy and should lead to separation from whatever might hinder His program of blessing. See Paul’s use of this account in Galatians 4:21-31.

Verses 22-34

13. Abimelech’s treaty with Abraham 21:22-34

"This scene occurs at the same time as the events of Scene 6 [Genesis 21:1-21] but focuses on different characters and tensions. This second conflict with Abimelech creates a bracket around the Isaac birth narrative. Whereas the first conflict, Scene 5 (Genesis 20:1-18), concerned jeopardy of the seed, the second conflict, Scene 7 (Genesis 21:22-34), concerns jeopardy of the land (i.e., well rights)." [Note: Waltke, Genesis, p. 298.]

God’s blessing of Abraham resulted in his material prosperity. In response to Abimelech’s initiative Abraham agreed to make a covenant of peaceful coexistence. This treaty enabled Abraham to serve and worship God freely in the Promised Land.

The writer may have included this incident in the text partially because it records the testimony of a Gentile king to God’s faithfulness (Genesis 21:22) and Abraham’s strong testimony to God’s faithfulness (Genesis 21:32-33). It also sets the stage for Isaac’s dealings with Abimelech (ch. 26).

Since Abraham had become a powerful individual in the land by God’s blessing, Abimelech initiated a bilateral treaty with him for his own protection. This was evidently the same Abimelech that Abraham had dealt with previously (ch. 20). They made a parity covenant (i.e., between equals, Genesis 21:31-32). This was a remarkable admission of Abraham’s standing and blessing by God and an expression of Abimelech’s confidence in the future existence of the patriarch’s family.

The birth of Isaac seems to have produced a much stronger faith in Abraham (cf. Genesis 21:14). Note his immediate response to God’s instructions to him from then on (cf. Genesis 22:3).

"Phicol" (Genesis 21:22) seems to have been a title rather than a proper name, probably of Anatolian origin. [Note: On the origin of Phicol, Abimelech’s army commander, see J. D. Ray, "Two Etymologies: Ziklag and Phicol," Vetus Testamentum 36:3 (July 1986):358-59; and Wenham, Genesis 16-50, pp. 91-92. Cf. 26:26.]

Wells were extremely important in the life of semi-nomads like Abraham (Genesis 21:25). [Note: See Clark Youngblood, "Wells," Biblical Illustrator (Fall 1986), pp. 41-49.]

Beersheba, one of the more important sites throughout Old Testament times, meaning "oath of seven" or "oath-well," became Abraham’s possession with the payment of seven ewe lambs (Genesis 21:28; cf. Genesis 26:33). [Note: See William G. Dever, "Beersheba," Biblical Illustrator (Spring 1983), pp. 56-62.]

Critics of the historicity of the patriarchal narratives have pointed out references to the Philistines in Genesis (Genesis 21:32; Genesis 21:34; Genesis 26:1) as evidence that the Bible contains errors. It is common knowledge that the Philistines did not invade Palestine until about 1200 B.C. whereas Abraham evidently lived about 800 years earlier. One explanation is that since the Philistines of Genesis were peaceful and those of Judges and later were warlike perhaps the same name describes an earlier group of people. They may have resembled the later thirteenth-century Philistines who also emigrated from the Aegean area into Palestine. [Note: Kitchen, Ancient Orient . . ., p. 80; Edward E. Hindson, The Philistines and the Old Testament, pp. 94-95.] On the other hand perhaps the Philistines of 2000 B.C. were Minoan and peaceful whereas those of 1200 were Mycenean and warlike. [Note: Barker, p. 134. See also Vassos Karageorghis, "Exploring Philistine Origins on the Island of Cyprus," Biblical Archaeology Review 10:2 (March-April 1984):16-28.]

"I suggest that the Philistines of Genesis represent the first wave of Sea Peoples from the Aegean, and that the later Philistines represent the last wave (cf. 1200 B.C.)." [Note: Hamilton, The Book . . . Chapters 18-50, p. 94.]

By planting a tree Abraham indicated his determination to stay in that region. Tamarisk trees (Genesis 21:33) were long-lived and evergreen. [Note: Mathews, Genesis 11:27-50:26, p. 282.] This tree was an appropriate symbol of the enduring grace of the faithful God whom Abraham recognized as "the Everlasting God" (El Olam). Abraham now owned a small part of the land God had promised him.

"By granting Abraham rights to a well, Abimelek had made it possible for Abraham to live there permanently and had acknowledged his legal right at least to water. In other words, after so many delays the promises of land and descendants at last seem on their way to fulfillment." [Note: Wenham, Genesis 16-50, p. 94.]

In contrast to Abraham’s fear of Abimelech (ch. 20) we now see him boldly standing up to this powerful king. His changed attitude evidently resulted from God’s grace in blessing the patriarch as He had promised.

"The reader is forced to ask why the author constantly draws attention to the fact that Abraham was dwelling with the Philistines during this time [cf. Genesis 21:34]. The purpose of such reminders may be to portray Abraham as one who had yet to experience the complete fulfillment of God’s promises." [Note: Sailhamer, The Pentateuch . . ., p. 177.]

Peaceful interpersonal relationships with those who acknowledge God enable the believer to proclaim his or her faith freely (cf. 1 Timothy 2:1-4).

Bibliographical Information
Constable, Thomas. DD. "Commentary on Genesis 21". "Dr. Constable's Expository Notes". 2012.