Set thy face toward the mountains of Israel - This is a new prophecy, and was most probably given after the four hundred and thirty days of his lying on his left and right side were accomplished. By Israel here, Judea is simply meant; not the ten tribes, who had long before been carried into captivity. Ezekiel uses this term in reference to the Jews only.
The mountains may be addressed here particularly, because it was on them the chief scenes of idolatry were exhibited.

Son of man, set thy face towards the mountains of Israel,.... Or cities of Israel, the inhabitants of them; not the ten tribes, for they had been carried captive long before this time, even in the times of Hezekiah; unless it can be thought that this prophecy is designed to show the reason of their captivity, which was their idolatry; or that it is directed to those of them which remained in the land, and were mixed with the other tribes; but rather the land of Judea is intended, in which were many mountains, and one part of it was called the hill country, Luke 1:39; and the mountains are mentioned, against which the prophet is ordered to direct his face, and look unto; partly because idolatry was much practised upon them; and partly to show the stupidity of the Jews, and the failure of the prophecy among them; that it was as well, or better, to speak to the mountains, than to them; for since they had so often put away the word of God from them, they were unworthy of it; wherefore such a direction to the prophet comes some degree of indignation and resentment:
and prophesy against them; as that the sword should be upon them, and the high places built upon them should be destroyed: or "unto them" (a); direct the prophecy to them; speak to them as if they were capable of hearing: or "concerning them", as the Syriac version; and so the Targum, concerning their desolation.
(a) "ad eos", V. L. Pagninus, Montanus; "ad illos", Piscator.

CONTINUATION OF THE SAME SUBJECT. (Ezekiel 6:1-14)
mountains of Israel--that is, of Palestine in general. The mountains are addressed by personification; implying that the Israelites themselves are incurable and unworthy of any more appeals; so the prophet sent to Jeroboam did not deign to address the king, but addressed the altar (1-Kings 13:2). The mountains are specified as being the scene of Jewish idolatries on "the high places" (Ezekiel 6:3; Leviticus 26:30).

The mountains - The inhabitants of the mountains, who were secure in their fastnesses.