“And I saw three unclean spirits like frogs come out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet.”
King James Version (KJV)
16:13 Out of the mouth of the dragon, the wild beast, and the false prophet - It seems, the dragon fights chiefly against God; the beast, against Christ; the false prophet, against the Spirit of truth; and that the three unclean spirits which come from them, and exactly resemble them, endeavour to blacken the works of creation, of redemption, and of sanctification. The false prophet - So is the second beast frequently named, after the kingdom of the first is darkened; for he can then no longer prevail by main strength, and so works by lies and deceit. Mahomet was first a false prophet, and afterwards a powerful prince: but this beast was first powerful as a prince; afterwards a false prophet, a teacher of lies. Like frogs - Whose abode is in fens, marshes, and other unclean places. To the kings of the whole world - Both Mahometan and pagan. To gather them - To the assistance of their three principals.
Re 16:13 I saw three unclean spirits like frogs [come] out of the mouth of the dragon. Let the reader observe there is an alliance of three powers described as the "dragon", the "beast", and the "false prophet". From their mouths came three unclean spirits, like frogs, who go forth to the kings of the earth, rally their forces under the banners of the three allied powers, and march them to the battle of the great day of the Almighty. We have met these three powers before, and know that these are really one, animated by one spirit, but appearing in different forms. The dragon, the Satan, wars against the woman, in the form of old Pagan Rome (Re 12:13-17); he then transfers this warfare to the seven-headed beast, the political world power shown both in the form of Imperial and Papal Rome (Re 13:7); this power was supported, reanimated when about to perish, by the lamb-like dragon who is the false prophet (Re 13:11). "As it were frogs" (Revised Version). Unclean, loathsome, suggesting the plagues of Egypt (Ex 8:2).