John the Apostle
Revelation 18:6ESV·traditional attribution

Pay her back as she herself has paid back others, and repay her double for her deeds; mix a double portion for her in the cup she mixed.

Matthew Henry Presbyterian @wholebiblehenry

The downfall and destruction of Babylon form an event so fully determined in the counsels of God, and of such consequence to his interests and glory, that the visions and predictions concerning it are repeated. 1. Here is another angel sent from heaven, attended with great power and lustre, Rev 18:1.

Commenting on Revelation 18:1-8

John Gill Reformed Baptist @doctorgill

Reward her even as she rewarded you,.... This is spoken to the people of God, who are before called out of Babylon; and the chief of them are the seven angels with the seven last plagues of the wrath of God, and the same with the ten kings that will burn the whore with fire; these are called upon to take vengeance, by way of...

Albert Barnes Presbyterian @notesbybarnes

Verse 6. Reward her even as she rewarded you. It is not said to whom this command is addressed, but it would seem to be to those who had been persecuted and wronged. Applied to mystical Babylon--Papal Rome --it would seem to be a call on the nations that had been so long under her sway, and among whom, from time to time, so much...