TSK · Genesis 17:19

And the angel of the LORD said unto her, Behold, thou [art] with child, and shalt bear a son, and shalt call his name Ishmael; because the LORD hath heard thy affliction.

And he said, I will certainly return unto thee according to the time of life; and, lo, Sarah thy wife shall have a son. And Sarah heard [it] in the tent door, which [was] behind him.

And Abraham called the name of his son that was born unto him, whom Sarah bare to him, Isaac.

Sojourn in this land, and I will be with thee, and will bless thee; for unto thee, and unto thy seed, I will give all these countries, and I will perform the oath which I sware unto Abraham thy father;

But the angel said unto him, Fear not, Zacharias: for thy prayer is heard; and thy wife Elisabeth shall bear thee a son, and thou shalt call his name John.

Now we, brethren, as Isaac was, are the children of promise.