Revelation 4:1; Revelation 8:6; Revelation 8:13; Revelation 9:14

Revelation 4:1

1 After this I looked, and, behold, a door was opened in heaven: and the first voice which I heard was as it were of a trumpet talking with me; which said,Come up hither, and I will shew thee things which must be hereafter.

Revelation 8:6

6 And the seven angels which had the seven trumpets prepared themselves to sound.

Revelation 8:13

13 And I beheld, and heard an angel flying through the midst of heaven, saying with a loud voice, Woe, woe, woe, to the inhabiters of the earth by reason of the other voices of the trumpet of the three angels, which are yet to sound!

Revelation 9:14

14 Saying to the sixth angel which had the trumpet, Loose the four angels which are bound in the great river Euphrates.