Poole on Revelation 9:13: The Sixth Trumpet
Verse 13: And the sixth angel sounded, and I heard a voice from the four horns of the golden altar which is before God…
[And the sixth, etc.] A signal given of new evils (Grotius, similarly Pareus).
[I heard one voice (or, a certain one [Beza, Piscator], namely, God’s [Durham]; or, Christ’s [Piscator, Durham]; or, the very Altar’s [Cotterius]) from the four horns (that is, corners [Zegers, Piscator]; that is, from its midst [Pareus], from the surface bounded by the four horns, so that it might be a Metonymy of adjunct [Piscator]: There is an allusion here and an agreement of number, four Angels in verse 14; four times, namely, an hour, a day, a month, a year, in verse 15; and here four horns [Forbes]) of the altar of gold (namely, of Incenses [Grotius, thus Beza, Drusius], by which Prayers are signified [Grotius, similarly Ribera]: Here also Aaron yearly supplicated, Exodus 30 [Ribera]: Thence this voice proceeds, as if it were the voice of the prayer of the Saints under the Altar, who were asking that the impious be punished by this plague [Menochius, similarly Tirinus]: The four horns denote the four points of the world, from all which prayers are raised to God, and His answers awaited: But on all these horns had been written the sins of men, as in Jeremiah 17:1, and therefore God publishes from them the sentence concerning the punishment of the world: For the sanctity of the Altar is of no benefit to the wicked, but provokes greater wrath of God against them [Cluverus]: Such were the sins of the impious that the very altar cries out against the impious and demands vengeance [Lapide]: One voice crying from the four horns indicates that from all corners of the earth one and the same judgment of its impiety sounds together and acts in unison [Cluverus]: Others: The Altar denotes the worship of God, as in Revelation 8:3; or, the Gospel, to which Horns are given, and those four in number; for that is the Power of God to every believer, from the four corners of the World, etc.; which, trampled upon by men, demanded that the four Angels, avengers of human impiety, arise [Cotterius]: That Altar was representing Christ [Pareus]: The power of Christ is shown to be sufficient to arouse the instruments of His justice: For from this Altar, both, the prayers of the saints ascend into the presence of God; and, the avenging flames are poured out upon the world [Forbes]: There were four horns on this Altar, Exodus 30:3: By these here understand all the places in which Jews, worshipping Christ, were in exile; for not all were at Pella: [The sense:] God, with the prayers of those exiles heard, who were ever eager to return to their ancestral habitations, decreed that the siege, delayed for a sufficiently long time, be hastened, so that, with those events finished which God willed to be finished, the armies might depart, and a safe return be granted into the farms and fields, and whatever towns were remaining: Because of the elect the days will be cut short, Matthew 24:22 [Grotius]) which is, etc., τοῦ ἐνώπιον, etc.] Which (understand, is [Beza], or, was, namely, in this Vision [Piscator]) before God (Piscator, Montanus, etc.). There is an allusion to the ancient type (Pareus). For this Altar was standing before the Ark, with only the veil placed between (Pareus, similarly Beza, Drusius), Exodus 30:6 (Beza).
A voice from the four horns of the golden altar: That is, from God, I heard him give a command, which voice is said to have proceeded from the golden altar, (in allusion to Exodus 30:3,) because there God received the prayers of his people; and this voice proceeding from that place, might signify the following judgment to come, in answer to the prayers of his servants’ souls from thence crying to him for vengeance. See Revelation 6:9, 10.
 Greek: Καὶ ὁ ἕκτος ἄγγελος ἐσάλπισε, καὶ ἤκουσα φωνὴν μίαν ἐκ τῶν τεσσάρων κεράτων τοῦ θυσιαστηρίου τοῦ χρυσοῦ τοῦ ἐνώπιον τοῦ Θεοῦ.  Revelation 6:9-11. Pella was a village on the eastern side of the Jordan, about half way between the River Jabbok and the Sea of Galilee.