Hebrews 11:18

Of whom it had been said, In Isaac shall thy seed be called:

Romans 9:7-8

Neither because they are the seed of Abraham, are they all children, 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
Neither because they are the seed of Abraham, are they all children, but in Isaac shall thy seed be called:
Hebrews 11:18
Of whom it had been said, In Isaac shall thy seed be called: