Genesis 21:13

And also of the son of the bondwoman will I make a nation, because he [is] thy seed [descendant].


(Geneva Bible) - As for the son of the bondwoman, I will make him (e) a nation also, because he is thy seed.
(e) The Ishmaelites shall come of him.

Genesis 21:12

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.


(Geneva Bible) -But God said unto Abraham, Let it not be grievous in thy sight for the child, and for thy bondwoman; in all that Sarah shall say unto thee, hear her voice, for in Isaac shall thy seed be (d) called.
(d) The promised seed shall be counted from Isaac, and not from Ishmael, Romans 9:7; Hebrews 11:18

Genesis 21:10

Wherefore she said unto Abraham, Cast out this bondwoman and her son: for the son of this  bondwoman shall not be heir with my son, [even] with Isaac.

(Geneva Bible) - Wherefore she said unto Abraham, (*) Cast out this bondwoman and her son, for the son of this bondwoman shall not be heir with my son Isaac.
(*) Galatians 4:30 .