But the son of the slave was born according to the flesh, while the son of the free woman was born through promise.
But what does it say? "The word is near you, in your mouth and in your heart" (that is, the word of faith that we proclaim);
For it is written that Abraham had two sons, one by a slave woman and one by a free woman.
By faith Sarah herself received power to conceive, even when she was past the age, since she considered him faithful who had promised.