So the four angels, who had been prepared for the hour and day and month and year, were released to kill a third of mankind.
Revelation 9:15
Surrounding context
9:14 saying to the sixth angel who had the trumpet, "Release the four angels who are bound at the great river Euphrates."
9:15 So the four angels, who had been prepared for the hour and day and month and year, were released to kill a third of mankind.
9:16 Now the number of the army of the horsemen was two hundred million; I heard the number of them.