@Xenophon @Ash_Kvetchum @Omega_Variant Both interpretations are valid— material and spiritual. Abraham became a father to many nations, literally. Far more than just those of Jacob's descendants, as we know. Ishmael received a blessing and promise. Esau received a blessing and promise. Both are Abraham's seed.
>It doesn't say spiritual father.
Common eschatological understanding suggests it does. Ellicott's commentary on the matter explains it as well, although this is less detailed than his OT commentary. Including Romans 4:16 and 4:17 because of context.