Verse 1
Genesis 21:1. The Lord visited Sarah — That is, was present with her in his mercy, power, and faithfulness, to perform his gracious promise of giving her a child.

Verse 2
Genesis 21:2. Sarah conceived — By faith Sarah received strength, (Hebrews 11:11,) to conceive seed, God, according to his promise, giving that strength. Abraham was old, and Sarah old, and both as good as dead, and then the promise took place.

Verse 4
Genesis 21:4. He circumcised his son — The covenant being established with him, the seal of the covenant, according to God’s command, was administered to him.

Verse 6
Genesis 21:6. Sarah said, God has made me to laugh — Not through diffidence and irreverence, as my own distrustful heart before made me to laugh; but through excess of holy joy. He hath given me both cause and a heart to rejoice. And it adds to the comfort of any mercy to have our friends rejoice with us in it, Luke 1:58. They that hear will laugh with me — Will rejoice in this instance of God’s power and goodness; and be encouraged to trust in him.

Verse 7
Genesis 21:7. Sarah should have given children suck — She says children, expecting, it seems, that, having received of God new strength, she would have more than one child. Here all mothers are taught their duty, which is to give their children suck if they be able. Not to do this is a sin against the God of nature, which no rank in life, no fortune nor business, can or will excuse.

Verse 9
Genesis 21:9. Sarah saw the son of the Egyptian, mocking — Mocking Isaac, no doubt, for it is said, with reference to this, Galatians 4:29, that “he that was born after the flesh, persecuted him that was born after the spirit.”

Verse 10
Genesis 21:10. Cast out the bond-woman — This was a type of the rejection of the unbelieving Jews, who, though they were the seed of Abraham, yet, because they submitted not to the gospel covenant, were unchurched and disfranchised. And that which above any thing provoked God to cast them off, was, their mocking and persecuting the gospel church, God’s Isaac, in its infancy.

Verse 11
Genesis 21:11. The thing was very grievous in Abraham’s sight — Because of his affection to his son, and God’s promise concerning him. He who, at God’s command, which he was bound to obey, afterward so cheerfully gave up Isaac, was not so ready to part with Ishmael, to gratify the passion of an angry woman. And probably he would have denied her desire, if God had not interposed. It is remarkable that it is not said the thing was grievous because of his wife; probably he hardly considered Hagar as properly his wife: or, at least, had not the affection for her a man ought to have for his wife. Hereby we may learn the excellence of God’s institutions, who appointed only one woman for one man, that each might, under God, have the entire interest in the other’s affections; and we may observe the evil of men’s inventions which brought polygamy into the world, whereby a man’s affections are divided into several and contrary streams. But probably it grieved Abraham that Ishmael had given such provocation, as well as that Sarah insisted on such a punishment.

Verse 13
Genesis 21:13. The casting out of Ishmael was not his ruin. He shall be a nation because he is thy seed — We are not sure that it was his eternal ruin. It is presumption to say, that all those who are left out of the external dispensation of God’s covenant are excluded from his spiritual mercies. Those may be saved who are not thus honoured.

Verse 14
Genesis 21:14. Abraham rose up early in the morning — Immediately, it seems, after he had received orders in the night visions to do this: and took bread and a bottle of water — All necessary provision seems to be here included, of which it is probable they had sufficient to have served them till they had come to Hagar’s friends in Egypt, if they had not lost their way. Ishmael, it is thought, was more than sixteen years of age at this time, yet the provisions were put upon Hagar’s shoulders, as being more inured to labour, and the lad was committed to her care.

Verses 17-19
Genesis 21:17-19. God heard the voice of the lad — We read not of a word that he said; but his sighs and groans, though not proceeding from true repentance, but extorted from him by his pressing calamity, cried aloud in the ears of the God of mercy. An angel was sent to comfort Hagar, and assure her that God had heard the voice of the lad. Arise, lift up the lad, and hold him in thy hand — God’s readiness to help us when we are in trouble must not slacken, but quicken our endeavours to help ourselves. He repeats the promise concerning her son, that he should be a great nation, as a reason why she should bestir herself to help him. She saw a well of water — Which, it seems, was near at hand, but had not been observed by her before. Thus she obtained the relief she most wanted.

Verse 20-21
Genesis 21:20-21. God was with the lad — This accounts for his preservation and support in that wilderness, in which, had not God been with him in an extraordinary manner, in answer to Abraham’s prayer, in all probability he must have perished.

Verse 31
Genesis 21:31. Beer-sheba — That is, the well of the oath, or the well of the seven, (for the word equally signifies either,) alluding to the seven ewe- lambs which Abraham set by themselves and gave to Abimelech. Probably when a covenant was solemnly made and confirmed by an oath, seven lambs or sheep were wont to be offered.

Verse 33
Genesis 21:33. And Abraham planted a grove — For a shade to his tent, or perhaps an orchard of fruit-trees; and there, though we cannot say he settled, for God would have him while he lived to be a stranger and a pilgrim, yet he sojourned many days. And called there on the name of the Lord — Probably in the grove he planted, which was his oratory, or house of prayer: he kept up public worship, in which, probably, some of his neighbours joined with him. Men should not only retain their goodness wherever they go, but do all they can to propagate it, and make others good. The everlasting God — Though God had made himself known to Abraham as his God in particular, yet he forgets not to give glory to him as the Lord of all, the everlasting God, who was before all worlds, and will be when time and days shall be no more.