John Calvin Commentary Genesis 25:19

"And these are the generations of Isaac, Abraham`s son. Abraham begat Isaac." — Genesis 25:19 (ASV)

These are the generations of Isaac. Because what Moses has said concerning the Ishmaelites was incidental, he now returns to the principal subject of the history, for the purpose of describing the progress of the Church. And in the first place, he repeats that Isaac’s wife was taken from Mesopotamia.

He expressly calls her the sister of Laban the Syrian, who was later to become the father-in-law of Jacob, and concerning whom he had many things to relate. But it is especially worth observing that he declares Rebekah to have been barren during the early years of her marriage.

And we shall later see that her barrenness continued, not for three or four, but for twenty years, so that her very despair of offspring might give greater glory to the sudden granting of the blessing.

But nothing seems less consistent with reason than that the propagation of the Church should be so small and slow. Abraham, in his extreme old age, received (as it seems) a slender solace for his long privation of offspring, in having all his hope centred in one individual. Isaac also, already advanced in years and approaching old age, was not yet a father.

Where, then, was the seed that should equal the stars of heaven in number? Who would not suppose that God was dealing deceitfully in leaving those houses empty and solitary, which, according to His own word, ought to be filled with a teeming population? But that which is recorded in the psalm must be accomplished in reference to the Church, that

he maketh her who had been barren to keep house, and to be a joyful mother of many children (Psalms 113:9).

For this small and contemptible origin, these slow and feeble advances, make more illustrious that increase, which later follows, beyond all hope and expectation, to teach us that the Church was produced and increased by divine power and grace, and not by merely natural means. It is indeed possible that God designed to correct or moderate any excess of attachment in Isaac. But this is to be observed as the chief reason for God’s conduct, that as the holy seed was given from heaven, it must not be produced according to the common order of nature, so that we learn that the Church did not originate in human effort, but flowed from the grace of God alone.