Tafsir of Al-Waqi'ah 56:49

Say: (in response to their denial and in establishment of the truth) "Indeed, the former and the later ones—among the nations, of whom you and your forefathers are a part."

The former are mentioned first for the sake of hyperbole in the rebuttal, as their denial of the resurrection of their forefathers is more intense than their denial of their own resurrection, while also observing the existential order.