14 saying to the sixth angel, the one having the trumpet, “Release the four angels, those having been bound at the great river Euphrates.”
Revelation 9:14 Cross References - BLB
Revelation 7:1
1 After these things I saw four angels standing upon the four corners of the earth, holding the four winds of the earth, so that no wind would blow on the earth, nor on the sea, nor on any tree.
Revelation 8:2
2 And I saw the seven angels who stand before God, and seven trumpets were given to them.
Revelation 8:6
6 And the seven angels having the seven trumpets prepared themselves, that they might sound the trumpets.
Revelation 9:15
15 And the four angels having been prepared for the hour and day and month and year were released, so that they might kill a third of mankind.
Revelation 16:12
12 And the sixth poured out his bowl upon the great river Euphrates, and its water was dried up, so that the way might be prepared of the kings of the rising of the sun.