Revelation:6:9-10
nkjv@Revelation:6:9 @ When He opened the fifth seal, I saw under the altar the souls of those who had been slain for the word of God and for the testimony which they held.
nkjv@Revelation:6:10 @ And they cried with a loud voice, saying, "How long, O Lord, holy and true, until You judge and avenge our blood on those who dwell on the earth?"