TSK · Genesis 21:3

And God said, Nay, but Sarah thy wife shall bear thee a son; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant for his seed after him. [

And God said unto Abraham, Let it not be grievous in thy sight because of the lad, and because of thy handmaid; in all that Sarah saith unto thee, hearken unto her voice; for in Isaac shall thy seed be called.

And these are the generations of Isaac, Abraham's son: Abraham begat Isaac:

Abraham begat Isaac; and Isaac begat Jacob; and Jacob begat Judah and his brethren;

neither, because they are Abraham's seed, are they all children: but, In Isaac shall thy seed be called.