Chapter 21
Chapter Outline
Birth of Isaac, Sarah's joy. (1–8)
Ishmael mocks Isaac. (9–13)
Hagar and Ishmael are cast forth, They are (14–21)
relieved and comforted by an angel.
Abimelech's covenant with Abraham. (22–34)Verses 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, ch. 17:17; 18:13. When the Sun of
comfort is risen upon the soul, it is good to remember how welcome the dawning of the day was.
When Sarah received the promise, she laughed with distrust and doubt. When God gives us the
mercies we began to despair of, we ought to remember with sorrow and shame our sinful distrust
of his power and promise, when we were in pursuit of them. This mercy filled Sarah with joy and
wonder. God's favours to his covenant people are such as surpass their own and others' thoughts
and expectations: who could imagine that he should do so much for those that deserve so little,
nay, for those that deserve so ill? Who would have said that God should send his Son to die for us,
his Spirit to make us holy, his angels to attend us? Who would have said that such great sins should
be pardoned, such mean services accepted, and such worthless worms taken into covenant? A short
account of Isaac's infancy is given. God's blessing upon the nursing of children, and the preservation
of them through the perils of the infant age, are to be acknowledged as signal instances of the care
and tenderness of the Divine providence. See Ps 22:9, 10; Ho 11:1, 2.
Verses 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.