In Isaac shall thy seed be called — Heb., in Isaac there shall be called to thee a seed: that is, the seed that shall especially be accounted thine, and which, as such, shall inherit the promises, will be that sprung from Isaac.
Related Commentaries of Genesis 21:12
Genesis 21:12
12 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.