Revelation 6:10

And they cried with a loud voice, saying, How long, O Lord, thou Holy One and true, dost thou not judge and avenge our blood on them that dwell upon the earth?

Revelation 18:20-24

Rejoice over her, thou heaven, and ye saints, and apostles, and prophets; for God hath avenged you on her.

Treasury of Scripture Knowledge

Summary

Because thou hast spoiled many nations, all the remnant of the people shall spoil thee; because of men's blood, and for the violence of the land, of the city, and of all that dwell therein.

Bible References

The violence

Revelation 6:10
And they cried with a loud voice, saying, How long, O Lord, thou Holy One and true, dost thou not judge and avenge our blood on them that dwell upon the earth?
Revelation 18:20
Rejoice over her, thou heaven, and ye saints, and apostles, and prophets; for God hath avenged you on her.