Revelation 9:14
telling the sixth angel with the trumpet, "Let loose the four angels who are bound at the great river Euphrates."
Revelation 16:12
The sixth poured out his bowl on the great river Euphrates, and its waters were dried up to prepare the way for the kings from the east.
Revelation 7:1
After that I saw four angels standing at the four corners of the earth, holding back the four winds from blowing on the earth or on the sea or on any tree.
Revelation 8:2
Then I saw seven trumpets being given to the seven angels who stand before God.
Revelation 8:6
And the seven angels with the seven trumpets prepared to blow their blasts.
Revelation 9:15
So the four angels were unloosed, who had been kept ready for that hour and day and month and year, to kill the third of men.