Galatians 4:24-28

Which things are an allegory: for these are the two covenants; the one from the mount Sinai, which gendereth to bondage, which is Agar.

For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children.

But Jerusalem which is above is free, which is the mother of us all.

For it is written, Rejoice, thou barren that bearest not; break forth and cry, thou that travailest not: for the desolate hath many more children than she which hath an husband.

Now we, brethren, as Isaac was, are the children of promise.