So she said to Abraham, “Cast out this slave woman with her son, for the son of this slave woman shall not be heir with my son Isaac.”
10. Cast out this bondwoman . Not only is Sarah exasperated against the transgressor, but she seems to act more imperiously towards her husband than was becoming in a modest wife. Peter shows, that when, on a previous occasion, she called Abraham lord, she did not do so feignedly; since he proposes her, as an example of voluntary subjection, to pious and chaste matrons.
The casting out of Ishmael is here considered of, and resolved on. I. Ishmael himself gave the occasion by some affronts he gave to Isaac his little brother, some think on the day that Abraham made the feast for joy that Isaac was safely weaned, which the Jews say was not till he was three years old, others say five.
Commenting on Genesis 21:9-13
And the thing was very grievous in Abraham's sight,.... The motion that Sarah made to turn out of his house Hagar and Ishmael was not agreeable to him, but the reverse; it seemed an ill thing to him; it was greatly displeasing to him, and he was unwilling to come into it: because of his son; his son Ishmael; not grieved and uneasy for what...