Revelation fortells of a time when those who trust completely in God and aren’t fooled by the beast, his image and the number of his name will sing “the song of Moses” and “the song of the Lamb” (Rev. 15:2–4).
We know of the “song of the Lamb” from Revelation 5. There’s the “song of Moshe” in Exodus 15 just after God saves Israel and destroys the Egyptian army in the Red Sea. There’s also another “song” of Moshe in Deuteronomy 32, and understanding it helps us understand apostle Paul’s terms “under [the] law” and “under grace.”