But, what if…

Prior to the Aqedah, the promise was stated in terms of the nations blessing one another by Abraham (12:3; 18:18). But here for the first time the blessing is connected to Abraham’s descendants: “By your offspring shall all the nations of the earth bless themselves” (22:18a).

This means that for the promise to be fulfilled, Abraham would need to have offspring. He would need to have obeyed the angel’s command to stop the sacrifice and spare Isaac. This is why the angel links the promise to the sparing of Isaac: “By your offspring shall all the nations of the earth bless themselves, because you have listened to my voice.” Simply put, if Abraham had not desisted from the sacrifice when the angel called from heaven, there would be no offspring by which the nations could bless themselves.—Abraham's Silence, 218 (emphasis original)

<idle musing>
Quite a provocative thought! I'll have to chew on that one for a while…
</idle musing>