Revelation 11:5 - Matthew Poole's English Annotations on the Holy Bible

And if any man will hurt them; that is, my faithful ministers, the two olive branches before mentioned, which fill the candlesticks with oil. Fire proceedeth out of their mouth, and devoureth their enemies: here is a plain allusion to the stories of Moses and Elijah, calling for fire from heaven; but God showeth, that the victory of his ministers under the gospel shall not be by a miraculous fire called for down from heaven, (as Elijah hurt the captains and their bands sent to apprehend him), but by fire out of their mouths; according to that, Jeremiah 5:14, Behold, I will make my words in thy mouth fire, and this people wood, and it shall devour them: see also Jeremiah 1:9,10. This also is according to Zechariah's vision before mentioned, and the revelation of the will of God in it, Revelation 11:6: Not by might, nor by power, but by my Spirit, saith the Lord of hosts. The meaning is, that they shall be too hard for them, either by their faithful, lively, and powerful preaching, or by their fervent prayers.