Yes and Yes........... It's the song of Moses and it is that which David is reflecting back upon and also that which John is seeing in the vision.
There is absolutely NOTHING in Revelation that is not in the LAW and the PROPHETS.
When Yahweh delivered the Israelite out of Egypt ( HEATHENS ), they was charged to REMEMBER that day and they song a NEW SONG.
Exodus 15:1
(( THEN SANG MOSES AND THE CHILDREN OF ISRAEL THIS SONG )) unto the LORD, and spake, saying, I will sing unto the LORD, for he hath triumphed gloriously: the horse and his rider hath he thrown into the sea.
Compare the two :
Exodus 15:2
The LORD is my strength and song, and he is become my salvation.
Psalm 98:1,2
O sing unto the LORD a new song; for he hath done marvellous things:
Revelation 15:3
And they sing the song of Moses.
Thus is it a song of PRAISE, DELIVERANCE and SALVATION over their enemies, a song of HOPE in the time of trouble.
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Moses redeem Israel from age 20, all that was able to go to war, after the death of Moses, no man knew the number of those that made it to Caanaland until John who saw it in the VISION said : " I HEARD THE NUMBER "
No, it is NOT! ! something to come: Rev.1:19 - John is writing about things that WAS / IS and is TO COME.........and: That which has been IS that which SHALL BE, there is no NEW THING UNDER THE SUN. Eccl.1:9 -10