Albert Barnes Commentary Zechariah 9:3

"And Tyre did build herself a stronghold, and heaped up silver as the dust, and fine gold as the mire of the streets." — Zechariah 9:3 (ASV)

And Tyre built herself a stronghold – she built it for herself, not for God, and trusted in it, not in God, and so its strength brought her the greater fall. The words in Hebrew express even more: “Tyre” (Zor), literally “the rock,” built herself “mazor,” a tower—a rock-like fort, as it were, a rock upon exceeding strength, binding her together. “The walls, 150 feet high and of proportionate breadth, compacted of large stones embedded in gypsum,” seemed to defy an enemy who could only approach her by sea.

“In order to make the wall twice as strong, they built a second wall ten cubits broad, leaving a space between of five cubits, which they filled with stones and earth.” Yet high walls do not only fence in; they also hem in. Mazor is both “a stronghold” and “a siege.” Wealth and strength, without God, only invite and embitter the plunderer and the conqueror.

And she heaped up silver as the dust, and fine gold as the mire of the streets – “Though he heap up silver as the dust,” Job says (Job 27:16). The King, Solomon, “made silver in Jerusalem as stones” (2 Chronicles 9:27). Through her manifold commerce she gathered to herself wealth, as abundant as the mire and the dust, and as valueless. “Gold and silver,” said a pagan, “are but red and white earth.” Her strength was her destruction. Tyre determined to resist Alexander, “trusting in the strength of the island, and the stores which they had laid up”—the strength within and without, of which the prophet speaks.