Minor Change / Major Impact
We already know that in Genesis 17 God appears to Abram after thirteen years of silence. We find several crucial changes here. The incredible promise—that Abram would have another son besides Ishmael—comes in verse 16. Before that, God announces to Abram that He will make a covenant with him and his descendants forever; but even before that, He changes his name to Abraham. God is saying: “your name shall be Abraham, for I have made you a father of many nations.” Thus, as we also know, this new name, “Abraham”אַבְרָהָם (avraham), reflects God’s plan and promise: “a father of many nations,” אַב־הֲמוֹן גּוֹיִם, (av hamon goyim).
But what about Sarah? God also tells Abraham that Sarai, his wife, would be called “Sarah” and will bear him a son. Rashi, a renowned medieval commentator, explains: “you shall not call her name Sarai” – which means “my princess” – “but Sarah shall be her name”, and she will be a princess over all. The change is still minor, it’s still one letter – moreover, it’s still the same letter ה – but the significance of this change can’t be overestimated: from now on the names of Abraham and Sarah will indicate that God’s plan covers the entire multitude of their descendants. The direction of this change is still the same: from one particular family – to many nations.
Biblical names carried an important weight. One of the biggest losses we experience while reading the Bible in translation is the loss of the meaning of the names. When God gives a new name, His plan is contained within this name.
The Breaking News
Quite honestly, I don’t think that the message of Genesis 17:16 – about Sarah’s son – was a very good news for Abraham. At least, not in the way we are used to reading it: Look, finally, Isaac is coming! No, Abraham had a son already. As we know, he was perfectly happy with this son; his heart was full of Ishmael, and he wasn’t even sure he wanted another son. After all, he was an old man and he was not sure he would have room in his life for another son. He heard the magnificent promises of God to his descendants and he naturally thought—and was absolutely happy to think—that all those promises referred to Ishmael. Certainly, he was obedient to the Lord, as always, and did not argue with Him when He announced His will; but I don’t think he was especially thrilled about the news of this new baby. In a sense, the breaking news of Genesis 17:16 was an unexpected and almost unwelcome change in Abraham’s world.
Then God said to Abraham, “As for Sarai your wife, you shall not call her name Sarai, but Sarah shall be her name. And I will bless her and also give you a son by her; then I will bless her, and she shall be a mother of nations; kings of peoples shall be from her.”
So unexpected, so inconceivable—and probably so unwelcome also—was this news, that Abraham was not in a hurry to tell Sarah about it, or so it seems at least. We don’t know how much time passed between God’s appearance to Abraham in chapter 17 and His appearance by the trees of Mamre, in chapter 18. According to midrashim, just a few days had passed and Abraham was not even completely recovered after his circumcision that occurred at the end of chapter 17. We don’t find any clue in the Torah, but even if this was the case and only a few days had passed since Abraham’s last encounter with God, it still seems that during these days, he didn’t find time to share with Sarah this great news that God had told him–and breaking news, indeed! For when Sarah hears of it in chapter 18, she laughs with that famous laughter “within herself,” that shows more clearly than anything else that this is the very first time she has heard about it.
Perhaps Abraham just didn’t take it seriously? Perhaps he thought he had misunderstood the Lord and there was no need even to talk to Sarah about it and raise her hopes when there was actually no hope for her. I can almost imagine Abraham thinking that he had misunderstood the Lord on this occasion: After all, it was indeed a very peculiar case and demanded a great deal of faith to believe that his 90-year old barren wife would bear him a child. However, just a few chapters later, when Abraham is asked to sacrifice Isaac—again, a very peculiar request—Abraham doesn’t hesitate or think even for a moment that he has misunderstood God. In my opinion, Abraham heard God very clearly; he knew His voice perfectly well and their communication was crystal clear. If Abraham decided not to share the news he had heard from the Lord with Sarah, it could mean only one thing: It wasn’t such happy news for him, at least to begin with, and he didn’t want to talk about it.
Isaac- Son of Promise!
Please don’t misunderstand me. I am not saying that Abraham wasn’t happy about the birth of Isaac or that he didn’t love his youngest son. Of course he loved Isaac dearly; there is no doubt about that. What I am saying is that he had loved Ishmael for thirteen years, before he had even heard of Isaac, and in all those thirteen years, he hadn’t expected anyone else to take his place. Thirteen years is a long time, and for all this time, Ishmael had been his only son. Certainly, after chapter 18 and after the Lord visited Sarah as He had said, and the Lord did to Sarah as He had spoken, for Sarah conceived and bore Abraham a son in his old age, and after this supernatural birth, Abraham knew, beyond a shadow of a doubt, who was to be the son of promise.
Whatever his feelings might have been at the beginning, Abraham was a man of faith and knew how to obey God—he had proved that many times before, and he proved it again in this story. Did that mean, however, that he stopped loving Ishmael or loved him less now? Undoubtedly, when Isaac was born, he found a place in Abraham’s heart – what baby would not melt the heart of his father, especially if this father is 100 years old? And yet, that didn’t mean that Ishmael occupied a smaller place in his heart now: Abraham still loved his firstborn as strongly and as tenderly as he had loved him all those years, when Ishmael had been his only child. In out next and final post on Abraham, we will see the amazing – and in a sense, very unique – biblical proof of that.
 Gen. 17:15-16
 Rabbinic expositional commentaries
 Gen. 21:1