Revelation 14:3; Revelation 14:4

3 And they sang a new song before the throne and before the four living creatures and the elders. No one could learn the song except the 144,000 who had been redeemed from the earth.

4 These are those who did not defile themselves with women, for they remained virgins. They follow the Lamb wherever he goes. They were purchased from among mankind and offered as firstfruits to God and the Lamb.