Hebrews 11:18

of whom it was told him, that in Isaac shall thy seed be called:

Romans 9:7-8

Nor because they are the seed of Abraham, are they all children of promise: but "in Isaac shall thy seed be called."

Treasury of Scripture Knowledge

Summary

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.

Bible References

In isaac

Romans 9:7
Nor because they are the seed of Abraham, are they all children of promise: but "in Isaac shall thy seed be called."
Hebrews 11:18
of whom it was told him, that in Isaac shall thy seed be called: