John heard something from the altar that is before God,
“Then the sixth angel sounded: And I heard a voice from the four horns of the golden altar which is before God, saying to the sixth angel who had the trumpet, ‘Release the four angels who are bound at the great river Euphrates’” (Revelation 9:13-14).
The sixth angel brought the second woe. (See Revelation 8:13.)
John heard a voice from the four horns of the golden altar before God, which is significant, and here is why.
Revelation 8:3 showed an angel offering the prayers of the saints on the golden altar that is before the throne of God. The sixth trumpet is in response to those prayers.
The voice commanded the sixth angel to release the four angels bound at the Euphrates River, a great boundary, holding back a great adversary.
Keep reading the text to see what happens, but know this, that our prayers have a huge influence with God.