211 And Jehovah hath looked after Sarah as He hath said, and Jehovah doth to Sarah as He hath spoken; 2 and Sarah conceiveth, and beareth a son to Abraham, to his old age, at the appointed time that God hath spoken of with him; 3 and Abraham calleth the name of his son who is born to him, whom Sarah hath born to him—Isaac; 4 and Abraham circumciseth Isaac his son, 'being' a son of eight days, as God hath commanded him. 5 And Abraham 'is' a son of a hundred years in Isaac his son being born to him, 6 and Sarah saith, 'God hath made laughter for me; every one who is hearing laugheth for me.' 7 She saith also, 'Who hath said to Abraham, Sarah hath suckled sons, that I have born a son for his old age?'
8 And the lad groweth, and is weaned, and Abraham maketh a great banquet in the day of Isaac's being weaned;
9 and Sarah seeth the son of Hagar the Egyptian, whom she hath borne to Abraham, mocking, 10 and she saith to Abraham, 'Cast out this handmaid and her son; for the son of this handmaid hath no possession with my son—with Isaac.' 11 And the thing is very wrong in the eyes of Abraham, for his son's sake; 12 and God saith unto Abraham, 'Let it not be wrong in thine eyes because of the youth, and because of thy handmaid: all that Sarah saith unto thee—hearken to her voice, for in Isaac is a seed called to thee. 13 As to the son of the handmaid also, for a nation I set him, because he 'is' thy seed.'
Matthew Henry's Commentary on Genesis 21:1-13
Commentary on Genesis 21:1-8
(Read Genesis 21:1-8)
Few under the Old Testament were brought into the world with such expectations as Isaac. He was in this a type of Christ, that Seed which the holy God so long promised, and holy men so long expected. He was born according to the promise, at the set time of which God had spoken. God's promised mercies will certainly come at the time which He sets, and that is the best time. Isaac means "laughter," and there was good reason for the name, Psalm 22:9,10; Hosea 11:1,2.
Commentary on Genesis 21:9-13
(Read Genesis 21:9-13)
Let us not overlook the manner in which this family matter instructs us not to rest in outward privileges, or in our own doings. And let us seek the blessings of the new covenant by faith in its Divine Surety. Ishmael's conduct was persecution, being done in profane contempt of the covenant and promise, and with malice against Isaac. 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. Mocking is a great sin, and very provoking to God. And the children of promise must expect to be mocked. Abraham was grieved that Ishmael should misbehave, and Sarah demand so severe a punishment. But God showed him that Isaac must be the father of the promised Seed; therefore, send Ishmael away, lest he corrupt the manners, or try to take the rights of Isaac. The covenant seed of Abraham must be a people by themselves, not mingled with those who were out of covenant: Sarah little thought of this; but God turned aright what she said.