Revelation 7:9

7:9 After these things I looked, and here was an enormous crowd that no one could count, made up of persons from every nation, tribe, people, and language, standing before the throne and before the Lamb dressed in long white robes, and with palm branches in their hands.

Revelation 14:3

14:3 and they were singing a new song before the throne and before the four living creatures and the elders. No one was able to learn the song except the one hundred and forty-four thousand who had been redeemed from the earth.