Isaiah 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 Samuel 10:4-5). Prisoners and slaves were shaved as a mark of dishonor, and this condition signified insult and disrespect. [Note: Watts, p. 107.] 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.