Revelation 6:10-11

and they cried out with a loud voice, saying, “How long, holy and true Lord, will you not judge and avenge our blood from those who live on the earth?” And to each one of them a white robe was given, and it was said to them that they should rest yet a short time, until the number of their fellow slaves and their brothers who were about to be killed as they had been were completed also.