Revelation 14:2-3

2Then I heard a loud sound which came from heaven. The noise was like water that pours along a river very fast. It was like the loud noise of thunder. The sound was like people who were making music with harps.

3The 144,000 people were singing a new song that they had learned. They sang it in front of the throne. They sang in front of the four beings that are alive and in front of the leaders. Only these 144,000 people could learn the new song. They are the people that God had saved from among the people who lived on the earth.