Galatians 4:23

"But he who was of the bondwoman was born after the flesh; but he of the freewoman was by promise."

Cross References (ranked by relevance)

Through faith also Sara herself received strength to conceive seed, and was delivered of a child when she was past age, because she judged him faithful who had promised.

Romans 10:8

But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach;