TSK · Genesis 21:2

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 he said, I will certainly return unto thee when the season cometh round; and, lo, Sarah thy wife shall have a son. And Sarah heard in the tent door, which was behind him.

And I took your father Abraham from beyond the River, and led him throughout all the land of Canaan, and multiplied his seed, and gave him Isaac.

And after these days Elisabeth his wife conceived; and she hid herself five months, saying,

And he gave him the covenant of circumcision: and so [Abraham] begat Isaac, and circumcised him the eighth day; and Isaac [begat] Jacob, and Jacob the twelve patriarchs.

For it is written, that Abraham had two sons, one by the handmaid, and one by the freewoman.