Charles Ellicott Commentary Revelation 16:1

"And I heard a great voice out of the temple, saying to the seven angels, Go ye, and pour out the seven bowls of the wrath of God into the earth." — Revelation 16:1 (ASV)

And I heard . . .—A great voice is heard out of the temple; it bids the angels pour out their vials into the earth; later on (Revelation 16:17) the voice is heard saying, It is done. The voice is then said to come from the throne; it seems likely that the voice of the first verse is the same—the divine voice from the throne itself.