The casting out of Ishmael was not his ruin. He shall be a nation because he is thy seed We are not sure that it was his eternal ruin. It is presumption to say, that all those who are left out of the external dispensation of God's covenant are excluded from his spiritual mercies. Those may be saved who are not thus honoured.
Related Commentaries of Genesis 21:13
Genesis 21:13
13 And also of the son of the bondwoman will I make a nation, because he is thy seed.