I interpret this verse also of the covenant by which the Jews had entangled themselves, when they willingly joined themselves to the Assyrians; for this was a sure sign of distrust, when they so desired foreign aid, as if they had been deprived of God's protection. And it would be absurd to explain this verse of idolatries, since the prophets were not accustomed to speak in this way, that the people committed fornication with the Assyrians, because they imitated their superstitions and perverse worship. As, therefore, we formerly saw that the Jews had defiled themselves with idols, and prostituted themselves to impious ceremonies, forgetful of God's law; so now the Prophet accuses them of a different kind of pollution, since they eagerly sought for aid from all quarters, as if God had not sufficient strength for their protection. For otherwise there was no religious reason for their not making peace with the Assyrians; but when they saw themselves oppressed by the kings of Israel and Syria, then they thought of sending for the Assyrians; and this was like thrusting God from his place. (2 Kings 16:7-9.) For God was willing to defend the land with extended wings, and to cherish the Jews as a hen does her brood, as Moses says, (Deuteronomy 32:11.) Now, in thinking themselves exposed to any danger, they really throw off the help of God. It is not surprising, then, that the Prophet says, that they had polluted themselves with the Assyrians, because they were not satisfied. He pursues the simile on which we have dwelt sufficiently; for he blames the Jews for their insatiable lust, just as when a woman is not content with a single follower, and attracting a crowd obtrudes herself without modesty or delicacy, and sells herself to wickedness. Such was the licentiousness of the Jews, that they united many acts of pollution together. They had already departed from the true faith in making a treaty with the Egyptians, and they added another imagination, that it was useful to have the Assyrians in alliance with them: hence that unbridled lust which the Prophet metaphorically rebukes. It follows --

Compare the marginal reference. Idolatry, spiritual adultery, invariably accompanied these unholy alliances, and brought with it disaster and ruin.

Thou hast played the whore also with the Assyrians,.... By entering into alliances with them, and worshipping their idols; which was done in the times of Ahaz, who sent to Tiglathpileser king of Assyria for help, and to Damascus for the fashion of the altar there, and built one according to it, 2-Kings 7:10;
because thou wast unsatiable; not content with the alliance and idolatries of the Egyptians:
yea, thou hast played the harlot with them; with the Assyrians:
and yet couldest not be satisfied; with their idols, and the worship of them, but sought out for new gods, and new modes of worship; like a lewd woman, who having prostituted herself to one, and to another, yet remains insatiable, and seeks out for other lovers.

unsatiable--Not satisfied with whoredoms with neighbors, thou hast gone off to the distant Assyrians, that is, hast sought a league with them, and with it adopted their idolatries.