For I, saith the LORD, will be unto her a wall of fire round about, and will be the glory in the midst of her.
For I, saith the Lord, will be unto her a wall of fire round about - (cf. Zechariah 2:4, "Jerusalem shall be ... as towns without walls"). Yet, as a city needs some wall, I, Yahweh, will act as a wall of fire which none durst approach (Zechariah 9:8, I, who am "Salvation" itself, will be thy wall of salvation; Psalms 35:3; Isaiah 26:1).
And will be the glory in the midst of her - not only a defense from foes outside, but a glory within (Isaiah 60:19; Revelation 21:23). The same combination of "glory and defense" is found in Isaiah 4:5, alluding to the pillar of cloud and fire which defended and enlightened Israel in the desert. Compare the "chariots of fire round about Elisha" in Dothan, 2 Kings 6:17. As God is to be her "glory" so shall she be His crown of "glory" (Isaiah 62:3).