Parallel

Revelation 9:15

King James Version (1769 Blayney revision, with Apocrypha) · Berean Standard Bible

9:15

And the four angels were loosed, which were prepared an hour, and a day, and a month, and a year, for to slay the third part of men.

So the four angels who had been prepared for this hour and day and month and year were released to kill a third of mankind.