John saw the Lamb standing on Zion Mountain with 144,000 redeemed people, who were marked with God’s seal. They were singing a new song that only the redeemed could sing.

Revelation 14:1-5

14 But then I saw the one who is like a lamb standing on Zion Hill in Jerusalem. With him were 144,000 people. His name and his Father’s name had been written {He had written his name and his Father’s name} on their foreheads. 2 I heard a sound from heaven, which was as loud [SIM] as the sound of a huge waterfall (OR, a great/wide river of rushing water) and which was also as loud as [SIM] mighty thunder. The sound that I heard was like the sound that people make when they are playing their harps. 3 The 144,000 people were singing a new song while they stood in front of the throne, in front of the four living creatures, and in front of the elders. Only the 144,000 people, the ones who have been {whom the one who is like a lamb has} redeemed/bought from among the people on the earth, could learn that song. No one else could learn the song that they sang. 4 Those 144,000 are the people who are spiritually pure, like virgins are morally pure. They have not ◄defiled themselves/made themselves impure► [MET] by worshipping any false god. They are the ones who accompany Jesus, the one who is like a lamb, wherever he goes. They represent all those whom he has redeemed/bought for God from among the people of earth, in order that he might offer them to God and to himself. 5 Those people never lie when they speak [MTY], and they never act immorally.