Then Abraham - laughed - I am astonished to find learned and pious men considering this as a token of Abraham's weakness of faith or unbelief, when they have the most positive assurance from the Spirit of God himself that Abraham was not weak but strong in the faith; that he staggered not at the promise through unbelief, but gave glory to God, Romans 4:19, Romans 4:20. It is true the same word is used, Genesis 18:12, concerning Sarah, in whom it was certainly a sign of doubtfulness, though mixed with pleasure at the thought of the possibility of her becoming a mother; but we know how possible it is to express both faith and unbelief in the same way, and even pleasure and disdain have been expressed by a smile or laugh. By laughing Abraham undoubtedly expressed his joy at the prospect of the fulfillment of so glorious a promise; and from this very circumstance Isaac had his name. יצחק yitschak, which we change into Isaac, signifies laughter; and it is the same word which is used in the verse before us: Abraham fell on his face, ויצחק vaiyitschak, and he laughed; and to the joy which he felt on this occasion our Lord evidently alludes, John 8:56 : Your father Abraham Rejoiced to see my day; and he saw it, and was Glad. And to commemorate this joy he called his son's name Isaac. See note on Genesis 21:6.

Then Abraham fell upon his face,.... In reverence of the divine Being, and as amazed at what was told him:

and laughed; not through distrust and diffidence of the promise, as Sarah did, for he staggered not at that through unbelief, but for joy at such good news; and so Onkelos renders it, "and he rejoiced", with the joy of faith; it may be our Lord refers to this in John 8:56; he saw Christ in the promise of Isaac, and rejoiced that he should spring from his seed: the Targums of Jonathan and Jerusalem paraphrase it, "and he wondered"; he was amazed at the grace of God that gave him such a promise, and he was astonished at the power of God that must be exerted in the fulfilment of it: and therefore it follows:

and said in his heart; within himself, without expressing anything as to be heard and understood by any creature; but the omniscient God knew what he said, and the language of it, whether of unbelief or not:

shall a child be born unto him that is an hundred years old? not that he was now a full an hundred years old, he was ninety nine, and going in his hundredth year; but then he would be, as he was, an hundred years old when this child was born to him, Genesis 21:5. It had been no unusual thing for a child to be born to a man when an hundred, and even many hundred years old, but it was so in Abraham's time; though indeed after this we read that Abraham himself had six sons by Keturah, when, his natural strength was afresh invigorated, and his youth was renewed like the eagle's; and besides Abraham said this, not so much with respect to himself, though his age was a circumstance that served to heighten the wonder, as with respect to Sarah, and the circumstances in which she was, who was to bear this son to him:

and shall Sarah, that is ninety years old, bear? and with whom it had ceased to be after the manner of women, which made it more difficult of belief how it could be. Some think that Abraham said this, as somewhat doubting of it, until he was more strongly assured by the Lord that so it would be indeed, as is expressed in Genesis 17:19; but meeting with no reproof for what he said and did, as Sarah, it seems to show the contrary.

Then Abraham fell upon his face, and {f} laughed, and said in his heart, Shall a child be born unto him that is an hundred years old? and shall Sarah, that is ninety years old, bear?

(f) Which proceeded from a sudden joy, and not from lack of faith.

17:17 Then Abraham fell on his face, and laughed - It was a laughter of delight, not of distrust. Now it was that Abraham rejoiced to see Christ's day, now he saw it and was glad, John 8:56, for as he saw heaven in the promise of Canaan, so he saw Christ in the promise of Isaac, and said, Shall a child be born to him that is an hundred years old? - He doth not here speak of it, as at all doubtful, for we are sure he staggered not at the promise, Rom 4:20, but as wonderful, and that which could not be effected but by the almighty power of God.

17. Abraham fell upon his face, and laughed-It was not the sneer of unbelief, but a smile of delight at the improbability of the event (Ro 4:20).

17:15-22 Here is the promise made to Abraham of a son by Sarai, in whom the promise made to him should be fulfilled. The assurance of this promise was the change of Sarai's name into Sarah. Sarai signifies my princess, as if her honour were confined to one family only; Sarah signifies a princess. The more favours God confers upon us, the more low we should be in our own eyes. Abraham showed great joy; he laughed, it was a laughter of delight, not of distrust. Now it was that Abraham rejoiced to see Christ's day; now he saw it and was glad, Joh 8:56. Abraham, dreading lest Ishmael should be abandoned and forsaken of God, put up a petition on his behalf. God gives us leave in prayer to be particular in making known our requests. Whatever is our care and fear, should be spread before God in prayer. It is the duty of parents to pray for their children, and the great thing we should desire is, that they may be kept in covenant with Him, and may have grace to walk before him in uprightness. Common blessings are secured to Ishmael. Outward good things are often given to those children of godly parents who are born after the flesh, for their parents' sake. Covenant blessings are reserved for Isaac, and appropriated to him.