John Chrysostom
From the offspring of the servant girl, I will bring forth a mighty nation, for he is your descendant. Thus, follow her instructions and heed her words.
But I will make the son also of the bondwoman a great nation, because he is thy seed.
וְגַ֥ם אֶת־בֶּן־הָאָמָ֖ה לְג֣וֹי אֲשִׂימֶ֑נּוּ כִּ֥י זַרְעֲךָ֖ הֽוּא׃
3 Church Fathers comment on this verse
From the offspring of the servant girl, I will bring forth a mighty nation, for he is your descendant. Thus, follow her instructions and heed her words.
Since he is your child, you feel a deep concern that he might suddenly be lost and suffer in separation. He will not be without My grace. Our God provides for everyone, empowering both the just and the unjust; He sends rain upon the just and the unjust alike (Matthew 5:45).
Ishmael was predetermined (Gen. 16:11) to Hagar, not to Abraham. Regarding the son of the servant, I will establish a great nation; for he too is part of your lineage. This highlights the notion that having a noble father does not guarantee privilege. Blessed abundantly by God, he shares those blessings with many descendants far and wide. Consequently, it is clear that parents who fail to seek God's favor act against their own interests and those of their children; likewise, children who neglect their heritage belittle themselves through either injustice and ungratefulness or by admitting they are wild branches stemming from a wild root.
Passages read together with this verse.