Then the LORD asked Abraham, "Why did Sarah laugh and say, 'Can I really have a child when I am so old?'

Is anything too hard for the LORD? As I said, nine months from now I will return, and Sarah will have a son."

Then he said, "I will give you so many descendants that no one will be able to count them.

The angel of the LORD called to Abraham from heaven a second time,

"I make a vow by my own name---the LORD is speaking---that I will richly bless you. Because you did this and did not keep back your only son from me,

But I will keep my covenant with your son Isaac, who will be born to Sarah about this time next year."

and she became pregnant and bore a son to Abraham when he was old. The boy was born at the time God had said he would be born.

and Elisha said to her, "By this time next year you will be holding a son in your arms." "Oh!" she exclaimed. "Please, sir, don't lie to me. You are a man of God!"

But, as Elisha had said, at about that time the following year she gave birth to a son.

I will bless her, and I will give you a son by her. I will bless her, and she will become the mother of nations, and there will be kings among her descendants."

But God said, "No. Your wife Sarah will bear you a son and you will name him Isaac. I will keep my covenant with him and with his descendants forever. It is an everlasting covenant.

But I will keep my covenant with your son Isaac, who will be born to Sarah about this time next year."

and she became pregnant and bore a son to Abraham when he was old. The boy was born at the time God had said he would be born.

The LORD's angel appeared to her and said, "You have never been able to have children, but you will soon be pregnant and have a son.

and after your son is born, you must never cut his hair, because from the day of his birth he will be dedicated to God as a nazirite. He will begin the work of rescuing Israel from the Philistines."

But the angel said to him, "Don't be afraid, Zechariah! God has heard your prayer, and your wife Elizabeth will bear you a son. You are to name him John.

This means that the children born in the usual way are not the children of God; instead, the children born as a result of God's promise are regarded as the true descendants.

For God's promise was made in these words: "At the right time I will come back, and Sarah will have a son."

His son by the slave woman was born in the usual way, but his son by the free woman was born as a result of God's promise.

Now, you, my friends, are God's children as a result of his promise, just as Isaac was.