Genesis 21:11

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 he had done; not for committing idolatry, as the Targum of Jonathan suggests, or for mocking at Isaac; but for what was proposed to be done to him, the ejection of him from his house, because of the great love he had for him, and the great concern he had for his education, and that he might enjoy the blessing promised him, he, was loath to have him cast out of his family: no concern is expressed for Hagar, though both by what God said to Abraham, and by the provision he made for her, he had a regard unto her; but his chief concern was for his son, who perhaps had a greater share in his natural affections than as yet Isaac had; nor did express so much reluctance when he was bid to him up, as he did at this time, that being at the command of God, this at the instance of his wife, and which he supposed only proceeded from passion and resentment: the Hebrew writers say x, that of all the evils that came upon Abraham this was the hardest and most grievous in his sight.

x Pirke Eliezer, c. 30.