Thematic Bible: Isaac born to

And Sarah conceived, and bore Abraham a son in his old age, at the appointed time of which God had spoken to him. And Abraham called the name of his son who was born to him, whom Sarah bore to him, Isaac.

For it is written that Abraham had two sons; one of the maid servant, and one of the free woman. But he that was of the maid servant was born according to flesh, and he that was of the free woman through the promise. Which things have an allegorical sense; for these are two covenants: one from mount Sinai, gendering to bondage, which is Hagar. read more.
For Hagar is mount Sinai in Arabia, and corresponds to Jerusalem which is now, for she is in bondage with her children; but the Jerusalem above is free, which is our mother. For it is written, Rejoice, thou barren that bearest not; break out and cry, thou that travailest not; because the children of the desolate are more numerous than those of her that has a husband. But ye, brethren, after the pattern of Isaac, are children of promise. But as then he that was born according to flesh persecuted him that was born according to Spirit, so also it is now. But what says the scripture? Cast out the maid servant and her son; for the son of the maid servant shall not inherit with the son of the free woman.