Charles Ellicott Commentary Zechariah 2:5

"For I, saith Jehovah, will be unto her a wall of fire round about, and I will be the glory in the midst of her." — Zechariah 2:5 (ASV)

A wall of fire. —This verse is not intended to discourage the building of walls to Jerusalem, something that was actually done under Nehemiah (445 B.C.), but is simply a solemn promise of God’s protection. Many indeed were the troubles that fell on the city in the times that intervened between the days of Zechariah and those of our Lord; but still, abundant proof was given that God had not forgotten His promise to shield it. Such troubles, as at other periods of the history of the Jews, were merely chastisements, and even those not in proportion to their transgressions. (For the figurative use of the expression “wall,” see 1 Samuel 25:16.)