God did not explicitly explain the delay, but the Bible shows the promise was fulfilled at His own appointed time.
God's Word never gives the reason for the long wait in detail, but the biblical record shows the birth of Isaac came at 'the set time' (Genesis 21:2). Les Feldick notes that Abraham had almost 50 years of promises while nothing seemed to happen, which led Abraham and Sarah to act through Hagar. That human effort produced Ishmael, not the promised son, yet God repeated His promise and fulfilled it through Isaac.
Genesis 17:19 — God specifically names Isaac as the promised son before his birth, showing the wait would end with a specific child born through Sarah.
Genesis 21:1-2 — The birth of Isaac at 'the set time' shows the long wait was part of God's appointed timing.
Romans 4:18 — It describes Abraham's faith against hope while the promised son had not yet come.
Scripture records that when Abraham was a hundred years old and Sarah ninety, Abraham fell on his face and laughed, wondering if a child could be born to him (Genesis 17:17). God's answer was direct: 'Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him' (Genesis 17:19). When Abraham then asked that Ishmael might live before God, God did not change His answer; the covenant was established with Isaac. Later, Genesis 21:1-2 says the Lord visited Sarah as He had said and did unto her as He had spoken, and she conceived and bare Abraham a son in his old age at the set time of which God had spoken. Scripture does not give a specific reason why the wait lasted so long, but it records that the birth came at the time God had set and that Abraham believed in hope against hope (Romans 4:18).
Les Feldick explains that Abraham was near eighty when Ishmael was born and one hundred when God's promise was fulfilled with Isaac, so Abraham had almost fifty years to 'sweat the promises' while nothing happened. Looking at those circumstances, Les says he can hardly blame Abraham for listening to Sarah and having a child by her slave girl, because from a human perspective 'God wasn't doing anything.' Yet the child of human effort, Ishmael, was not the promised son. Les stresses that when God tells Abraham that Sarah will bear Isaac, that is an 'I will' from God, and an 'I will' from God is a promise. What God promises He will not let fail. Even though Abraham was nearing one hundred and Sarah nearly ninety, the promise was valid because God said He would do it. Les uses the phrase 'His wheels grind slowly, but surely' to describe God's timing. At the set time, Sarah conceived and Isaac was born.
Les Feldick teaches that Abraham was near eighty when he received Ishmael, and he was one hundred when Isaac was born, with Sarah at ninety. That meant Abraham had almost fifty years of promises while it looked like nothing was happening. The biblical record adds that when the child came at last, it was at the set time of which God had spoken (Genesis 21:2).
According to Les, because God had not acted after so many years, Abraham listened to Sarah and had a child by her slave girl Hagar. Les describes this as human effort coming in because it seemed like God was doing nothing. That child was Ishmael, and he was not the son God had promised. Abraham even asked that Ishmael might live before God, but God said Sarah herself would bear Isaac.
No. Les Feldick emphasizes that the long wait did not make God's word fail. When God says 'I will,' it is a promise, and what God promises He will not let fail. At the precise time God had set, Sarah conceived and bore Isaac in Abraham's old age (Genesis 21:2).
Why Christ Had to Be Virgin Born — Romans 9 & Genesis 3:15
of Abraham, as well as the seed of woman, "...and to thy seed, who is Christ." And so whenever you see that term, the seed of the woman, in one form or another it's always a reference to Jesus Christ, the One who was promised way back in Genesis chapter 3.
Almost 50 Years of Waiting
Abraham was near 80 when Ishmael was born and 100 when Isaac came; after almost 50 years of promises, Abraham took human action through Sarah's slave girl, but God still worked in His own slow, sure way.
Isaac Is the Promised Son
When Abraham suggested Ishmael could fulfill God's promise, God refused and said Sarah would bear Isaac; an 'I will' from God is a promise that Isaac would be the promised son.
Against Hope, Abraham Believed in Hope
Even when both Abraham and Sarah were far beyond childbearing age and the promise seemed impossible, Abraham had genuine hope and believed God would bring it to pass.
God's Promise Cannot Fail
Despite Abraham's age nearing 100 and Sarah nearing 90, the promise remained valid because God declared He would do it, and what God promises He will not let fail.
Abraham's Plea for Ishmael
At 99, Abraham knew Sarah would still need nine months of gestation, and he feared God would take Ishmael's life; his plea shows his concern, but God reaffirmed that Sarah would bear Isaac.
The Sovereign God Chooses Isaac
When the age of Abraham and Sarah made the birth seem impossible, God answered by promising that Sarah herself would bear Isaac and that His covenant would be with Isaac for an everlasting covenant.
The Birth at the Set Time
God visited Sarah as He had said and she conceived and bore Isaac at the precise time God had set, showing the wait ended at God's appointed time.
Genesis 17:17: Then Abraham fell upon his face, and laughed, and said in his heart, Shall a child be born unto him that is an hundred years old? and shall Sarah, that is ninety years old, bear?
Shows how impossible the promise seemed when Abraham was 100 and Sarah 90.
Genesis 17:19: And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him.
God's direct promise that Sarah, not Hagar, would bear Isaac.
Genesis 21:1: And the LORD visited Sarah as he had said, and the LORD did unto Sarah as he had spoken.
Confirms God fulfilled His Word to Sarah after the wait.
Genesis 21:2: For Sarah conceived, and bare Abraham a son in his old age, at the set time of which God had spoken to him.
Explicitly shows the birth happened at God's set time.
Romans 4:18: Who against hope believed in hope, that he might become the father of many nations; according to that which was spoken, so shall thy seed be.
Shows Abraham's faith in the promise despite its apparent impossibility.
Les Feldick says Abraham had almost 50 years between Ishmael's birth when Abraham was near 80 and Isaac's birth when he was 100. The reason is not explained in detail, but the delay led Abraham and Sarah to act through Hagar, and God still fulfilled His promise at His set time.
No. Les stresses that what God promises He will not let fail. Even when Abraham was nearly 100 and Sarah nearly 90, the promise was valid because God said He would do it.
In Genesis 17:18-19, when Abraham asked that Ishmael might live before God, God said Sarah would bear a son and he was to be called Isaac, and the covenant would be established with Isaac. Les points out that God's 'I will' is a promise, and Isaac was that promised son.
Watch the Teaching: Why Christ Had to Be Virgin Born — Romans 9 & Genesis 3:15