19 God said, "No, but Sarah, your wife, will bear you a son. You shall call his name Isaac. I will establish my covenant with him for an everlasting covenant for his seed after him.
*Minor differences ignored. Grouped by changes, with first version listed as example.
Sarah thy wife shall bear thee a son indeed Some take the adverb 'vl (abal,) to mean Truly.' Others, however, more rightly suppose it to be used for increasing the force of the expression. For God rouses the slumbering mind of his servant; as if he would say, The sight of one favor prevents thee from raising thyself higher; and thus it happens that thou dost confine thy thoughts within too narrow limits. Now, therefore, enlarge thy mind, to receive also what I promise concerning Sarah. For the door of hope ought to be sufficiently open to admit the word in its full magnitude.' And I will establish my covenant with him He confines the spiritual covenant to one family, in order that Abraham may hence learn to hope for the blessing before promised; for since he had framed for himself a false hope, not founded on the word of God, it was necessary that this false hope should first be dislodged from his heart, in order that he might now the more fully rely upon the heavenly oracles, and might fix the anchor of his faith, which before had wavered in a fallacious imagination, on the firm truth of God. He calls the covenant everlasting, in the sense which we have previously explained. He then declares that it shall not be bound to one person only, but shall be common to his whole race, that it may, by continual succession, descend to his posterity. Yet it may seem absurd, that God should command Ishmael, whom he deprives of his grace, to be circumcised. I answer; although the Lord constitutes Isaac the firstborn and the head, from whom he intends the covenant of salvation to flow, he still does not entirely exclude Ishmael, but rather, in adopting the whole family of Abraham, joins Ishmael to his brother Isaac as an inferior member, until Ishmael cut himself off from his father's house, and his brother's society. Therefore his circumcision was not useless, until he apostatized from the covenant: for although it was not deposited with him, he might, nevertheless, participate in it, with his brother Isaac. In short, the Lord intends nothing else, by these words, than that Isaac should be the legitimate heir of the promised benediction.
And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an (g) everlasting covenant, [and] with his seed after him.
(g) The everlasting covenant is made with the children of the Spirit. A temporary promise is made with the children of the flesh, as was promised to Ishmael.
And God said, Sarah thy wife shall bear thee a son indeed,.... This is repeated for the confirmation of it, and thus expressed to remove all doubt about it, if any there were, that hung upon Abraham's mind; as well as to let him know that the promise of a son by Sarah was not to be superseded by his prayer for Ishmael, for whom he might have a greater flow of natural affection than for his unborn son, in whom his seed should be called:
and thou shall call his name Isaac; which signifies "laughter"; and which name was given him from the laughter of Abraham at the promise of him, and not from the laughter of Sarah, which as yet was not; wherefore Josephus (p) is wrong when he suggests, that Isaac had this name from Sarah's laughing at God's saying, that she should bear a son: though his birth was matter of laughter and joy to both, as it was to all good people that heard of it, Genesis 21:8. So Polyhistor (q) from Melo, an Heathen writer, speaking of Abraham, says, that of his married or lawful wife one son was born to him, whose name in Greek is "Gelos", that is, laughter. Isaac is one of those the Jews (r) observe had his name given him before he was born; see Gill on Genesis 16:11,
and I will establish my covenant with him, for an everlasting covenant, and with his seed after him; the covenant of circumcision just made with Abraham, the promise of the land of Canaan to him and his posterity, and of the Messiah that should spring from him, until whose coming this covenant would continue, and therefore called everlasting.
(p) Antiqu. l. 1. c. 12. sect. 2. (q) Apud Euseb. Evangel. Praepar. l. 9. c. 19. p. 421. (r) Pirke Eliezer, c. 32. Shalshalet Hakabala, fol. 2. 1.
The blessings of the covenant are reserved for Isaac, but common blessings were abundantly promised to Ishmael; and though the visible Church did not descend from his family, yet personally he might, and it is to be hoped did, enjoy its benefits.
*More commentary available at chapter level.