A Galilean scholar lectured before Rabbi Chisda: Blessed be the Merciful One who gave a three-fold Torah (consisting of Torah, Prophets and Scriptures) to a three-fold people (comprised of Kohanim, Levites and Israelites) through a third-born (Moses, the third child of Amram and Jocheved) on the third day (of separation) in the third month...
Talmud, Shabbat 88a
