But Sarah saw the son of Hagar the Egyptian, whom she had borne to Abraham, laughing. – Genesis 21:9
She saw him playing with Isaac, so the LXX., and, in play, mocking him. Ishmael was fourteen years older than Isaac; and, when children are together, the elder should be careful and tender of the younger: but it argued a very base and sordid disposition in Ishmael to be abusive to a child that was no way a match for him. Note, 1. God takes notice of what children say and do in their play, and will reckon with them if they say or do amiss, though their parents do not. 2. Mocking is a great sin, and very provoking to God. 3. There is a rooted remaining enmity in the seed of the serpent against the seed of the woman. The children of promise must expect to be mocked. This is persecution, which those that will live godly must count upon. 4. None are rejected and cast out from God but those who have first deserved it. Ishmael is continued in Abraham’s family till he becomes a disturbance, grief, and scandal to it. Matthew Henry.