Genesis 21:1

The Lord visited Sarah - That is, God fulfilled his promise to Sarah by giving her, at the advanced age of ninety, power to conceive and bring forth a son.

BIRTH OF ISAAC. (Gen 21:1-13) the Lord visited Sarah--The language of the historian seems designedly chosen to magnify the power of God as well as His faithfulness to His promise. It was God's grace that brought about that event, as well as the raising of spiritual children to Abraham, of which the birth of this son was typical [CALVIN].

And the Lord visited Sarah as he had said,.... To Abraham, Gen 17:16; in a way of mercy and kindness, by fulfilling his promise, giving strength to conceive and bear a child; see Sa1 2:21, and the Lord did unto Sarah as he had spoken; which intends the same thing in different words; and the repetition is made to cause attention to God's fulfilment of his promise, who is always faithful to his word, even in things very difficult and seemingly impossible, as in the present case: hence the Targums of Jonathan and Jerusalem paraphrase it, God did a wonder or wonders for Sarah in causing her to conceive when she was so old, and in such circumstances as she was.

Birth of Isaac. - Jehovah did for Sarah what God had promised in Gen 17:6 (cf. Gen 18:14): she conceived, and at the time appointed bore a son to Abraham, when he was 100 years old. Abraham gave it the name of Jizchak (or Isaac), and circumcised it on the eighth day. The name for the promised son had been selected by God, in connection with Abraham's laughing (Gen 17:17 and Gen 17:19), to indicate the nature of his birth and existence. For as his laughing sprang from the contrast between the idea and the reality; so through a miracle of grace the birth of Isaac gave effect to this contrast between the promise of God and the pledge of its fulfilment on the one hand, and the incapacity of Abraham for begetting children, and of Sarah for bearing them, on the other; and through this name, Isaac was designated as the fruit of omnipotent grace working against and above the forces of nature. Sarah also, who had previously laughed with unbelief at the divine promise (Gen 18:12), found a reason in the now accomplished birth of the promised son for laughing with joyous amazement; so that she exclaimed, with evident allusion to his name, "A laughing hath God prepared for me; every one who hears it will laugh to me" (i.e., will rejoice with me, in amazement at the blessing of God which has come upon me even in my old age), and gave a fitting expression to the joy of her heart, in this inspired tristich (Gen 21:7): "Who would have said unto Abraham: Sarah is giving suck; for I have born a son to his old age." מלּל is the poetic word for דּבּר, and מי before the perfect has the sense of - whoever has said, which we should express as a subjunctive; cf. Kg2 20:9; Psa 11:3, etc.

Long-looked-for comes at last. The vision concerning the promised seed is for an appointed time, and now, at the end, it speaks, and does not lie; few under the Old Testament were brought into the world with such expectation as Isaac was, not for the sake of any great person eminence at which he was to arrive, but because he was to be, in this very thin, a type of Christ, that seed which the holy God had so long promised and holy men so long expected. In this account of the first days of Isaac we may observe, I. The fulfilling of God's promise in the conception and birth of Isaac, Gen 21:1, Gen 21:2. Note, God's providences look best and brightest when they are compared with his word, and when we observe how God, in them all, acts as he has said, as he has spoken. 1. Isaac was born according to the promise. The Lord visited Sarah in mercy, as he had said. Note, No word of God shall fall to the ground; for he is faithful that has promised, and God's faithfulness is the stay and support of his people's faith. He was born at the set time of which God had spoken, Gen 21:2. Note, God is always punctual to his time; though his promised mercies come not at the time we set, they will certainly come at the time he sets, and that is the best time., 2. He was born by virtue of the promise: Sarah by faith received strength to conceive Heb 11:11. God therefore by promise gave that strength. It was not by the power of common providence, but by the power of a special promise, that Isaac was born. A sentence of death was, as it were, passed upon the second causes: Abraham was old, and Sarah old, and both as good as dead; and then the word of God took place. Note, True believers, by virtue of God's promises, are enabled to do that which is above the power of human nature, for by them th…

21:1-2 See 18:10.