TSK · Genesis 16:1

But Sarai was barren; she [had] no child.

¶ And Abram said, Lord GOD, what wilt thou give me, seeing I go childless, and the steward of my house [is] this Eliezer of Damascus?

And God said unto Abraham, Let it not be grievous in thy sight because of the lad, and because of thy bondwoman; in all that Sarah hath said unto thee, hearken unto her voice; for in Isaac shall thy seed be called.

And Isaac intreated the LORD for his wife, because she [was] barren: and the LORD was intreated of him, and Rebekah his wife conceived.

And they had no child, because that Elisabeth was barren, and they both were [now] well stricken in years.

Which things are an allegory: for these are the two covenants; the one from the mount Sinai, which gendereth to bondage, which is Agar.