In an interesting twist to the story, the Dwarves play not only the part of Ishmael, but briefly, the role of Isaac as well: “Then Aulë took up a great hammer to smite the Dwarves; and he wept. But Ilúvatar had compassion upon Aulë and his desire, because of his humility… And the voice of Ilúvatar said to Aulë: ‘Thy offer I accepted even as it was made…’” As Verlyn Flieger comments in her Splintered Light, “Aulë’s unquestioning acceptance of Eru’s chastisement and his willingness to destroy his creatures recalls the unquestioning obedience of biblical Abraham and his willingness to sacrifice his son Isaac at his God’s command.” That it is only after Aulë has offered—and in a symbolic sense might be said even—to destroy the Dwarves that Ilúvatar accepts them as part of his plan, might be further compared to the institution of circumcision which Yahweh establishes with Abraham between the births of Ishmael and Isaac, an act in which some commentators have seen a form of ritual castration whereby Abraham was led to renounce in faith his own efforts at accomplishing God’s purposes by the works of the flesh. In the end, of course, Aulë no more literally destroys the Dwarves than Abraham literally cuts off or kills either of his two sons, yet Aulë does have to witness his Dwarves subjected to a kind of death when they are buried “in darkness and under stone,” all the while trusting in Ilúvatar’s promise of their future “resurrection,” much as Abraham is required to receive Isaac from the “deadness,” first, of the womb of Sarah (Rom. 4:19) and later, of the altar and “tomb” that was Mt. Moriah (Heb. 11:11-12).
After Ilúvatar’s acceptance of Aulë’s sacrifice and his granting the Dwarves the gift of life, freedom, and speech, the Dwarves revert to their status as the Ishmaelites of the story. Despite Ishmael being technically Abraham’s firstborn son, it is Isaac whom Yahweh elects as the son of promise and the one with whom he would establish his covenant. In like manner, Ilúvatar decrees that Aulë’s Dwarves, although the first to be brought into being, nevertheless must not “come before the Firstborn of my design… They shall sleep now in the darkness under stone and shall not come forth until the Firstborn have awakened upon Earth.” At the same time, Yahweh’s election of Isaac and his seed does not altogether exclude the possibility of blessing for Ishmael, as Yahweh also promises Hagar to “multiply thy seed exceedingly, that it shall not be numbered for multitude” (Gen. 16:10). This relationship finds its parallel in Ilúvatar’s statement to Aulë that, “Even as I gave being to the thoughts of the Ainur at the beginning of the World, so now I have taken up thy desire and given to it a place therein… But when the time comes I will awaken them, and they shall be to thee as children…” Yet in both cases this blessing also comes with a foreshadowing of future conflict. As Ilúvatar does with Aulë’s Dwarves, Yahweh will give Ishmael a “place” in his “design,” but Ishmael will still be a “wild man” whose “hand will be against every man, and every man’s hand against him” (Gen. 16:12). Similarly, Ilúvatar tells Aulë that, notwithstanding his accommodation of the Dwarves within his plan, “in no other way will I amend thy handiwork, and as thou hast made it, so shall it be.” Thus, because “they were to come in the days of the power of Melkor, Aulë made the Dwarves strong to endure. Therefore they are stone-hard, stubborn, fast in friendship and in enmity, and they suffer toil and hanger and hurt of body more hardily than all other speaking peoples…” More than this, Ilúvatar warns Aulë how “often strife shall arise between thine and mine, the children of my adoption and the children of my choice.”
 Verlyn Flieger, Splintered Light: Language and Logos in Tolkien’s World, 100.