Commentary - Genesis 20:1-18

Bird's-eye view

In this remarkable and humbling account, we find Abraham, the great patriarch of faith, stumbling badly over the same sin he committed years before in Egypt. Fearing for his life, he passes off his wife Sarah as his sister, leading the pagan king Abimelech to take her into his harem. The entire episode serves as a powerful demonstration of God's sovereign grace and covenant faithfulness. God intervenes directly, not to congratulate Abraham on his cleverness, but to protect the purity of the promised line through Sarah. He does this by speaking to the pagan king in a dream, restraining him from sin, and bringing judgment on his household. The story is thick with irony: the pagan king behaves more honorably than the prophet of God, and the failing patriarch is the one whose intercession is required to bring healing. This is not a story about how to be a good husband. It is a story about how God, in His absolute sovereignty, preserves His redemptive plan despite the manifest faithlessness of His chosen instruments. It is a profound testimony that our salvation rests not on the strength of our grip on God, but on the strength of His grip on us.

This chapter is strategically placed right before the birth of Isaac in chapter 21. The promise is hanging by a thread, not because of external threats, but because of internal failure. Yet God proves Himself to be the great Protector of His promise. He is not a frantic deity, reacting to Abraham's blunders. He is the sovereign Lord, weaving even the sinful choices of men into His perfect tapestry, ensuring that His purposes will stand. The story strips Abraham of all glory so that God alone might be glorified.

Outline

Context In Genesis

This incident occurs at a moment of high tension in the Genesis narrative. In chapter 18, God had explicitly promised that Sarah would bear a son within the year. In chapter 19, God demonstrated His holy judgment by destroying Sodom and Gomorrah. One would expect Abraham's faith to be at an all-time high. Instead, we find him reverting to the same fear-driven deception he used with Pharaoh in Genesis 12. The placement of this story right before the fulfillment of the promise in Genesis 21 is crucial. It underscores the profound truth that the birth of Isaac, and by extension the entire plan of redemption, is a work of God's grace from start to finish, utterly independent of Abraham's moral consistency. The covenant does not advance because Abraham is worthy; it advances because God is faithful.

Key Issues

Sovereign Grace for a Stumbling Saint

One of the great dangers in reading the Bible is to turn the patriarchs into plaster saints. We want our heroes to be heroic in every respect. But the Holy Spirit, in His wisdom, has given us a brutally honest record. Abraham, the friend of God and the father of the faithful, was also a man who could be driven by craven fear. This is the second time he has pulled this stunt, endangering his wife and the covenant promise for the sake of his own skin. And what is God's response? It is not to discard Abraham and find a more reliable servant. No, God's response is to double down on His grace. He steps in to clean up the mess His servant has made. He protects Sarah, He instructs the pagan king, and He upholds the prophetic office of the very man who caused the crisis. This story is a beautiful, if unsettling, portrait of the gospel. God does not save respectable people. He saves sinners, and He remains faithful to them even when they stumble badly. Our standing with God is based on His promise, not our performance.

Verse by Verse Commentary

1-2 And Abraham journeyed from there toward the land of the Negev and settled between Kadesh and Shur; then he sojourned in Gerar. And Abraham said of Sarah his wife, “She is my sister.” So Abimelech king of Gerar sent and took Sarah.

Abraham is on the move, a sojourner as God commanded. But as soon as he settles in a new place, his old fears resurface. Gerar is Philistine territory, and Abraham sizes up the situation with the calculus of fear, not faith. He assumes the worst about the locals and implements his deceptive "she is my sister" policy. This is not a clever strategy; it is a profound failure of faith. He is willing to sacrifice his wife's purity to save his own life. Abimelech, the king, acts in a way that is entirely predictable. Hearing she is an unmarried woman, and seeing her beauty, he takes her for his harem. The crisis is entirely of Abraham's own making.

3 But God came to Abimelech in a dream of the night and said to him, “Behold, you are a dead man because of the woman whom you have taken, for she is married.”

Notice who God speaks to. He does not appear to His failing prophet Abraham to correct him. He appears to the pagan king Abimelech to warn him. God's intervention is swift and severe. The first words Abimelech hears from the Almighty are, "Behold, you are a dead man." God is not trifled with. The marriage covenant, and particularly this marriage which carries the seed of promise, is sacred. God holds Abimelech accountable for his actions, even though he was deceived. The objective reality is that Sarah is a married woman, and to touch her is a capital offense in the court of heaven.

4-5 (Now Abimelech had not come near her.) Then he said, “Lord, will You kill a nation, even though righteous? Did he not himself say to me, ‘She is my sister’? And she herself also said, ‘He is my brother.’ In the integrity of my heart and the innocence of my hands I have done this.”

The text parenthetically assures us that the line of promise was not defiled. Abimelech's response is remarkable. He addresses God as "Lord" and pleads his case. His defense is twofold. First, he appeals to God's justice: would God destroy a righteous people? Second, he appeals to his own integrity. He is not lying. He acted based on the information he was given by both Abraham and Sarah. He did what he did with a clear conscience, "in the integrity of my heart and the innocence of my hands." In this moment, the pagan king has a much firmer grasp on righteousness than the patriarch does.

6 Then God said to him in the dream, “Indeed, I know that in the integrity of your heart you have done this, and I also held you back from sinning against Me; therefore I did not let you touch her.

This verse is a gold mine of Reformed theology. God's response is astonishing. He affirms Abimelech's defense: "Yes, I know you acted with integrity." But then He pulls back the curtain to reveal the ultimate reality. The reason Abimelech did not consummate the union with Sarah was not ultimately due to his own integrity, but because God sovereignly restrained him. "I also held you back... I did not let you touch her." God did not merely foresee what would happen; He actively intervened in the heart and will of Abimelech to prevent the sin. This is God's meticulous providence at work, preserving His holy purposes by governing the affairs of men, even unbelieving men.

7 So now, return the man’s wife, for he is a prophet, and he will pray for you, and you will live. But if you do not return her, know that you shall surely die, you and all who are yours.”

The command is clear: return Sarah. The reason given is, on the surface, scandalous. Return her because her husband, the liar, "is a prophet." God upholds the sacred office even when the office-bearer is behaving shamefully. Abraham's standing is not based on his recent behavior, but on God's irrevocable calling. And in a stunning display of grace, God says that this failing prophet will be the instrument of Abimelech's deliverance. Abraham's prayer will save Abimelech's life. This is the logic of the gospel. We are not saved by our own righteousness, but by the intercession of another. The threat is also absolute: failure to comply will result in the death of Abimelech and his entire household.

8-9 So Abimelech arose early in the morning and called all his servants and told all these things in their hearing; and the men were greatly afraid. Then Abimelech called Abraham and said to him, “What have you done to us? And how have I sinned against you, that you have brought on me and on my kingdom a great sin? You have done to me things that ought not to be done.”

Abimelech's response is one of immediate, fearful obedience. He doesn't hit the snooze button. He gets up early and convenes his court. The fear of God falls upon them all. He then summons Abraham and delivers a sharp, and entirely justified, rebuke. His questions cut to the heart of the matter. "What have you done to us?" He rightly sees that Abraham's personal sin had corporate consequences, threatening to bring a "great sin" and disaster upon the whole kingdom. Abraham's actions were objectively wicked, "things that ought not to be done." The pagan king is schooling the prophet in basic ethics.

10-11 And Abimelech said to Abraham, “What have you seen, that you have done this thing?” And Abraham said, “Because I said, surely there is no fear of God in this place, and they will kill me because of my wife.

Abimelech presses for a motive. "What were you thinking?" Abraham's answer reveals the root of his sin: a failure of faith manifesting as a judgmental and cynical pragmatism. He made a damning assumption: "there is no fear of God in this place." He was utterly wrong. God was clearly at work in Gerar, and Abimelech and his men demonstrated a greater fear of God than Abraham did. His entire sinful strategy was built on a foundation of faithless prejudice.

12-13 Besides, she actually is my sister, the daughter of my father, but not the daughter of my mother, and she became my wife; and it happened when God caused me to wander from my father’s house, that I said to her, ‘This is the lovingkindness which you will show to me: everywhere we go, say of me, “He is my brother.” ’ ”

Abraham's defense continues, and it does not get better. He resorts to a technicality, a half-truth. While Sarah was his half-sister, the statement was designed to deceive Abimelech about the most crucial fact: that she was his wife. A half-truth deployed to create a false impression is a whole lie. Then, he compounds the error by revealing this was not a spontaneous lapse in judgment but a long-standing, premeditated policy of deception that he had imposed on his wife. He even seems to subtly blame God for it, noting it was "when God caused me to wander" that this plan was hatched. It is a pathetic and self-serving justification for his sin.

14-16 Abimelech then took sheep and oxen and male and female slaves and gave them to Abraham and returned his wife Sarah to him. And Abimelech said, “Behold, my land is before you; settle wherever it is good in your sight.” To Sarah he said, “Behold, I have given your brother one thousand pieces of silver; behold, it is your vindication before all who are with you, and before all you are cleared.”

Abimelech's response is one of astonishing magnanimity. He doesn't just return Sarah; he showers Abraham with gifts and offers him a place in the land. This is not a payoff; it is restitution and a public act of peace. His words to Sarah are particularly pointed. He gives the silver to her "brother," using Abraham's deceptive term with biting irony. The money serves as a public vindication for Sarah, a sign to everyone that she was taken innocently and has been restored with her honor intact. Abimelech is meticulously setting things right.

17-18 And Abraham prayed to God, and God healed Abimelech and his wife and his maidservants, so that they bore children. For Yahweh had utterly shut all the wombs of the household of Abimelech because of Sarah, Abraham’s wife.

And now, in the final ironic twist, the disgraced prophet must perform his prophetic duty. Abraham prays, and God hears and heals. This confirms to Abimelech that Abraham, for all his faults, truly is God's man. The final verse reveals the tangible nature of God's judgment. The curse for taking Sarah was already active in the form of mass infertility. The name of God, Yahweh, the covenant-keeping God, is used here to emphasize that this was a covenantal issue. God was jealously guarding Sarah, the mother of the promised seed. Abraham's prayer reverses the curse that his own sin had invited. It is a powerful picture of grace upon grace.

Application

This chapter should be a tremendous comfort to every believer who is painfully aware of his own sins and failures. Our security in Christ does not depend on our consistency. Abraham stumbled, and stumbled badly, yet God's covenant purpose did not miss a beat. God's faithfulness is the bedrock of our salvation. When we fail, the answer is not to justify ourselves with clever half-truths as Abraham did, but to confess our sin plainly.

We also see the profound sovereignty of God. He is not a spectator in heaven, hoping we get it right. He actively restrains evil and guides all things, even the sins of His people and the integrity of pagans, to His own appointed end. This should give us great confidence. The success of God's plan for this world does not rest on our shoulders, but on His.

Finally, we must learn the lesson that Abimelech learned. We must have a holy fear of God. We must take sin seriously, especially sin that harms others. And we must be willing to confront sin, even in our leaders, as Abimelech confronted Abraham. The story is a humbling reminder that God's grace is our only hope, and that He is pleased to display the strength of that grace through manifestly weak and flawed vessels, so that all the glory might go to Him.