Revelation 6:9-11 - The Fifth Seal
9 When he opened the fifth seal, I saw under the altar the souls of those who had been slain because of the word of God and the testimony they had maintained; 10 they cried out with a loud voice, "O Sovereign Lord, holy and true, how long before you judge and avenge our blood on those who dwell on the earth?" 11 Then each of them were given a white robe, and they were told to rest a little longer, until the number of their fellow servants and their brethren should be completed, who were to be killed as they had been.