From the Morning Bible readings

Then I looked, and lo, on Mount Zion stood the Lamb, and with him a hundred and forty-four thousand who had his name and his Father’s name written on their foreheads. And I heard a voice from heaven like the sound of many waters and like the sound of loud thunder; the voice I heard was like the sound of harpers playing on their harps, and they sing a new song before the throne and before the four living creatures and before the elders. No one could learn that song except the hundred and forty-four thousand who had been redeemed from the earth.

Revelation 14:1-13