Revelation 6:10-11

They cried in a loud voice, saying, “O Lord, holy and true, how long now before You will sit in judgment and avenge our blood on those [unregenerate ones] who dwell on the earth?” [Gen 4:10; Ps 79:10; 94:3; Zech 1:12] Then they were each given a white robe; and they were told to rest and wait quietly for a little while longer, until the number of their fellow servants and their brothers and sisters who were to be killed even as they had been, would be completed.