John Gill's Exposition of the Whole Bible
Isaiah 7:20
In the same day shall the Lord shave with a razor that is hired,.... Meaning the Assyrian monarch, whom he would use as an instrument in his hand to spoil and cut off the people of the Jews; who is compared to a "razor" for sharpness; and for the thorough work, and utter ruin and destruction, he should be the means of; and called a "hired" one, either in reference to the present Ahaz sent to the king of Assyria, by which he prevailed upon him to come and help him against the kings of Syria and Israel, 2 Kings 16:7 or to a reward given by the Lord to Nebuchadnezzar for the service in which he employed him, see Ezekiel 29:18:
[namely], by them beyond the river; not Nile, but Euphrates; even the Assyrians, Chaldeans, and Babylonians, who lived on the other side that river; which, with what follows, explains the simile of the razor:
by the king of Assyria; who ruled over those beyond the river:
the head, and the hair of the feet; and it shall also consume the beard; signifying that as a razor cuts off the hair entirely where it is applied, and leaves nothing behind, whether of the head, beard, or feet, or privy parts, which are meant by the latter; so the king of Assyria should carry all clean off captive out of the land of Judea; king, princes, nobles, and common people; those of the highest, and of the middling, and of the lowest class. The Targum is,
"in that time the Lord shall slay them as one is slain by a sharp sword, by clubs, and by saws, by those beyond the river, and by the king of Assyria; the king, and his army, and even his rulers, together shall he destroy.''
So Jarchi explains it. Several of the Jewish writers, as Aben Ezra, Abarbinel, and Kimchi k, explain this of the Angel of the Lord destroying Sennacherib's army, when before Jerusalem, in Hezekiah's time; so the latter interprets it: "the head"; the heads of his armies: "the hair of the feet"; the multitude of the people: "the beard"; the king, who died, not in the camp, but was killed by his sons in his own land; but this is not a prophecy of the destruction of the Assyrian army, but of the Jewish people by it; and the whole denotes the mean and low condition, the state of slavery and bondage, the Jews should be brought into; of which the shaving of the hair is the symbol; it was usual to shave the head and hair of such as were taken captive, as a sign of reproach and servitude; see 2 Samuel 10:4 l.
k Vid. T. Bab. Sanhedrin, fol. 95. 2. and 96. 1. l Vid. Lydium de re militari, l. 6. c. 6. p. 238, 239. Noldium, No. 937.