“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.”
King James Version (KJV)
18:6 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.
Re 18:6 Reward her even as she rewarded you. This is addressed to those who have meted out her judgments. The divine principle of judgments is that every one shall be rewarded "according" to his works. What they sow, "that" shall they reap. And double unto her double according to her works. This power shall have returned upon it in double portion what it has meted out to others.