Galatians 4:23
But the child of the slave-woman was born in the course of nature, while the child of the free woman was born in fulfillment of a promise.
Hebrews 11:11
Again, it was faith that enabled Sarah to conceive (though she was past the age for child-bearing), because she felt sure that he who had given her the promise would not fail her.
Romans 9:7-8
Nor, because they are Abraham's descendants, are they all his Children; but-'It is Isaac's children who will be called thy descendants.'
Romans 4:18-21
With no ground for hope, Abraham, sustained by hope, put faith in God; in order that, in fulfillment of the words-'So many shall thy descendants be,' he might become 'the Father of many nations.'
Romans 10:8
No, but what does it say? 'The Message of Faith' which we proclaim.
Galatians 4:28-29
As for ourselves, brothers, we, like Isaac, are children born in fulfillment of a promise.