Revelation 6:9-11

When the lamb opened the fifth seal, I saw under the altar the souls of those who had been slaughtered because of God’s word and the testimony they had given about him. They cried out in a loud voice, “Holy and true Master, how long before you judge and take revenge on those living on earth who shed our blood?” Each of the souls was given a white robe. They were told to rest a little longer until all their coworkers, the other Christians, would be killed as they had been killed.