'Bondwoman' in the Bible

For it is written that Abraham had two sons, one by the bondwoman and one by the free woman.

But the son by the bondwoman was born according to the flesh, and the son by the free woman through the promise.

But what does the Scripture say?“Cast out the bondwoman and her son,For the son of the bondwoman shall not be an heir with the son of the free woman.”

So then, brethren, we are not children of a bondwoman, but of the free woman.