The fall of Babylon being fixed, finished, and declared to be irrecoverable in the foregoing chapter, this begins with a holy triumph over her, in pursuance of the order given forth: Rejoice over her, thou heaven, and you holy apostles and prophets, Rev 18:20. They now gladly answer the call; and here you have, 1. The form of their thanksgiving, in that heavenly and most comprehensive word, Alleluia, praise you the Lord: with this they begin, with this they go on, and with this they end (Rev 19:4); their prayers are now turned into praises, their hosannas end in halleluias. 2. The matter of their thanksgiving: they praise him for the truth of his word, and the righteousness of his providential conduct, especially in this great event - the ruin of Babylon, which had been a mother, nurse, and nest of idolatry, lewdness, and cruelty (Rev 19:2), for which signal example of divine justice they ascribe salvation, and glory, and honour, and power, unto our God. 3. The effect of these their praises: when the angels and saints cried Alleluia, her fire burned more fiercely and her smoke ascended for ever and ever, Rev 19:3. The surest way to have our deliverances continued and completed is to give God the glory of what he has done for us. Praising God for what we have is praying in the most effectual manner for what is yet further to be done for us; the praises of the saints blow up the fire of God's wrath against the common enemy. 4. The blessed harmony between the angels and the saints in this triumphant song, Rev 19:4. The churches and their ministers take the melodious sound from the angels, and repeat it; falling down, and worshipping God, they cry, Amen, Alleluia.