6 sNot as though the word of God hath taken none effect. For tthey are not all Israel, which are of Israel: 7 uNeither, because they are the seed of Abraham, are they all children: but, wIn Isaac shall thy seed be called. 8 That is, They which are the children of the flesh, these are not the children of God: but xthe children of the promise are counted for the seed. 9 For this is the word of promise, yAt this time will I come, and Sara shall have a son.
Cited from Gen. 18:10.