'Freewoman' in the Bible

for it hath been written, that Abraham had two sons, one by the maid-servant, and one by the free-woman,

but he who is of the maid-servant, according to flesh hath been, and he who is of the free-woman, through the promise;

and the Jerusalem above is the free-woman, which is mother of us all,

but what saith the Writing? 'Cast forth the maid-servant and her son, for the son of the maid-servant may not be heir with the son of the free-woman;'