'Slave girl' in the Bible

she told Abraham, "Throw out this slave girl, along with her son, because this slave's son will never be a co-heir with my son Isaac!"

but God told Abraham, "Don't be troubled about the youth and your slave girl. Pay attention to Sarah in everything she tells you, because your offspring are to be named through Isaac.

Nevertheless, I will make the slave girl's son into a nation, since he, too, is your offspring."