Revelation 6:9 - 6:11
9 And when He opened the fifth seal, I saw underneath the altar the souls of those who had been slain because of the word of God, and because of the witness which they had maintained; 10 and they cried out with a loud voice, saying, “How long, O Master, holy and true? Will You not judge and avenge our blood on those who dwell on the earth?” 11 And a white robe was given to each of them; and it was told to them that they should rest for a little while longer, until the number of their fellow slaves and their brothers who were to be killed even as they had been, would be completed also.