Revelation 16:7

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;

Then I heard a loud voice from the sanctuary, saying to the seven angels, “Go and pour out on the earth the seven bowls of the wrath of God.”

because His judgments are true and righteous; for He has judged the great harlot who was corrupting the earth with her sexual immorality, and He has avenged the blood of His slaves shed by her hand.”

I bear witness to everyone who hears the words of the prophecy of this book: If anyone adds to them, God will add to him the plagues which are written in this book.