Zechariah 2:5

He confirms in this verse what I have just mentioned — that Jerusalem would be safe, though without any fortifications; for God alone would be sufficient for walls, for towers, for fortresses, according to what is said by other Prophets: “God will be to thee a wall and a fortress”, (Isaiah 26:1), again, “he will be to thee a stronghold”. It is, therefore, a sentence in accordance with other prophecies when Jehovah testifies, that he would be a wall of fire. We indeed know, that though walls may be high and thick, they may be scaled by enemies; but who will dare to throw himself into the fire? It is then the same as though God had spoken thus — “Though there will be no watchmen to defend Jerusalem, no soldiers to protect it, in short, no guardians whatever, yet I alone shall be sufficient; for I shall not only be a wall to keep off enemies, but I shall be also a fire to fill them with terror.”

He then adds, I will be for glory in the midst of her: as though he had said, “the real happiness of Jerusalem, within and without, will be in me alone and in my favor: within, in the midst of her I will be for glory; I will adorn her with every thing praiseworthy; and when there shall be any fear from the assault of enemies, I will be to her a wall of fire. For though she will not excel in strongholds and towers, and be without walls and fortresses, and shall be thus exposed to many evils, I shall yet strike all enemies with terror, so that they shall be kept afar off; and my Church shall be thus preserved safe, though destitute of all human aids, and without any defense.”

We now then perceive the meaning of the Prophet to be this — that though the Jews saw that they were but few in number, weak in strength, wretched and despised, they had yet reason to entertain hope; for though few returned from exile God was yet able to increase the Church and to make it a vast multitude, and that this was certain and decreed, for it was shown by the vision, that however unequal they were to their enemies, God was still sufficiently strong and powerful to defend them; and that however destitute they were of all blessings, God was still rich enough to enrich them, provided they relied on the blessing which he had promised; for he had engaged to render them happy and blessed within, and safe from enemies from without.