This section explains how the coming days would be the worse since the division of the kingdom (v. 17). Assyria was not just a powerful and brutal enemy, but it would be a tool in Yahweh's hand that He would use to discipline Judah.
7:18-19 Yahweh would summon the armies of Assyria and Egypt to do His bidding as one whistles (or hisses) at insects (cf. 5:26).106Enemy soldiers would swarm everywhere in Judah (cf. Judg. 6:1-6).
7:20 Judah's Sovereign would particularly use Assyria, as a barber uses a razor, to remove all the "hair"from Judah, to completely humiliate her (cf. 2 Sam. 10:4-5). Ahaz was already negotiating to hire Tiglath-pileser III, the king of Assyria, perhaps secretly at this time, to come and help Judah against the Syro-Ephraimitic alliance. However, Yahweh would hire the Assyrians (King Sennacherib) to do His will, implying that He would pay them for their efforts, which He did, not Ahaz.
7:21-22 In that day of woe instead of having flocks and herds, the Judahites would be fortunate to have only one heifer and a couple of sheep. There would be such a lack of abundance of milk that they would have to curdle it to preserve it. They would also have to resort to eating honey instead of the variety of food items that they previously enjoyed. Even though food and drink would be scarce, it would be good food and drink because God would provide for the people who survived the Assyrian invasion.
7:23-25 Valuable farm land would revert to wilderness (cf. 5:5-6), and it would only be good for hunting. Formerly cultivated land would be used for grazing because there would be so many briars and thorns.
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