Galatians 4:24
This story may be taken as an allegory. The women stand for two Covenants. One Covenant, given from Mount Sinai, produces a race of slaves and is represented by Hagar
Luke 1:7
But they had no child, Elizabeth being barren; and both of them were advanced in years.
Luke 1:36
And Elizabeth, your cousin, is herself also expecting a son in her old age; and it is now the sixth month with her, though she is called barren;
Treasury of Scripture Knowledge
Summary
Now Sarai Abram's wife bare him no children: and she had an handmaid, an Egyptian, whose name was Hagar.
Bare
Bible References
Bare
Luke 1:7
But they had no child, Elizabeth being barren; and both of them were advanced in years.