Transmission via Lineage
Since the fathers in the sacred lineage lived for the duration of several hundred years, such transmission could transpire more readily. Abraham, who faithfully made the way of salvation known to his seed, was able to learn third-handedly all that had transpired before him. Abraham was informed by Shem, with whom he lived contemporaneously, Shem from Methuselah, and Methuselah from Adam.
Wilhelmus à Brakel, The Christian's Reasonable Service, ed. Joel R. Beeke, trans. Bartel Elshout, vol. 1 (Grand Rapids, MI: Reformation Heritage Books, 1992), 23-24.