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 blood had been shed by her, to arise now in their might, and to inflict deserved vengeance. See the notes on Revelation 17:16-17.
And double unto her double according to her works - That is, bring upon her double the amount of calamity which she has brought upon others; take ample vengeance upon her. Compare for similar language, Isaiah 40:2, "She hath received of the Lord's hand double for all her sins." "For your shame ye shall have double," Isaiah 61:7.
In the cup which she hath filled - To bring wrath on others. See the notes at Revelation 14:8.
Fill to her double - Let her drink abundantly of the wine of the wrath of God - double what she has dealt out to others. That is, either let the quantity administered to her be doubled, or let the ingredients in the cup be doubled in intensity.

Reward her even as she rewarded you - These words are a prophetic declaration of what shall take place: God will deal with her as she dealt with others.

(7) Reward her even as she rewarded you, and double unto her double according to her works: in the cup which she hath filled fill to her double.
(7) The provocation of the godly, and the commandment of executing the judgment of God, stand on three causes which are here expressed: the unjust wickedness of the whore of Babylon, in this verse, her cursed pride opposing itself against God, which is the fountain of all evil actions, (Revelation 18:7) and her most just damnation by the sentence of God, (Revelation 18:8).

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 retaliation, for what she had done to them, in allusion to what is said of old Babylon, Jeremiah 1:15 and must be understood not of what she will have done to them personally, but to their predecessors in the faith of Christ in former ages; that as she had hated them, and made war with them, so now they should hate her, and make war with her; and as she had stripped them naked of their clothes, and spoiled them of their worldly goods and substance, so now they should strip her naked of her harlot's attire, of her gold, silver, and precious stones, and make her and her territories desolate; and as she has burnt many of the precious saints in the flames, as here in England, and elsewhere, so now they shall utterly burn her with fire; and as she has shed the blood of the righteous, and drank it, and been drunk with it, they shall give her blood to drink; and as she hath killed multitudes with the sword, so now shall they kill her and her children; see Revelation 13:12 nor is this contrary to the doctrine of Christ and his apostles, and the spirit of Christianity, which will not admit of revenge, Matthew 5:38 Romans 12:17 since this will not be private, but public revenge, inflicted by Christian princes and magistrates, who are ministers of God, and revengers to execute wrath on them that do evil:
and double unto her double according to her works: the meaning is not to inflict upon her a punishment doubly greater than her sins, for this would be contrary to the justice of God; nor does ever God punish men in this life more, but less, than their iniquities deserve; nor can any temporal punishment be doubly greater than sin, which deserves eternal death; and with this she will be punished hereafter, and therefore will not have her full punishment now, and much less a greater than her sins required; to which may be added, that this will be according to her works, her wicked works, and therefore will not exceed the demerit of her sins: but the sense is, that if it was possible to be done, they should use her with double severity to that she had used them with; seeing her sins deserved a severer treatment than even they had had from her; the phrase signifies an abundant and utter destruction, a punishment which was suitable and sufficient; see Isaiah 40:2 and it suggests that they should not spare her, nor pity her, but use her with the greatest severity imaginable, it being not possible to exceed her due deserts, or what her works required:
in the cup which he hath filled, fill to her double: not in the cup of her abominations, her errors, idolatries, and wickedness; but in the cup of afflictions and trouble, which she wrung out to the people of God, in that give her double portion: the sense is the same as before.

Addressed to the executioners of God's wrath.
Reward--Greek, "repay."
she rewarded--English Version reading adds "you" with none of the oldest manuscripts. But A, B, C, Vulgate, Syriac, and Coptic omit it. She had not rewarded or repaid the world power for some injury which the world power had inflicted on her; but she had given the world power that which was its due, namely, spiritual delusions, because it did not like to retain God in its knowledge; the unfaithful Church's principle was, "Populus vult decipi, et decipiatur." "The people like to be deceived, and let them be deceived."
double--of sorrow. Contrast with this the double of joy which Jerusalem shall receive for her past suffering (Isaiah 61:7; Zac 9:12); even as she has received double punishment for her sins (Isaiah 40:2).
unto her--So Syriac, Coptic, and ANDREAS. A, B, and C omit it.
in the cup-- (Revelation 18:3; Revelation 14:8; Revelation 17:4).
filled--literally "mixed."
fill to her double--of the Lord's cup of wrath.

Reward her - This God speaks to the executioners of his vengeance. Even as she hath rewarded - Others; in particular, the saints of God. And give her double - This, according to the Hebrew idiom, implies only a full retaliation.