Albert Barnes Commentary Hosea 7:9

"Strangers have devoured his strength, and he knoweth [it] not: yea, gray hairs are here and there upon him, and he knoweth [it] not." — Hosea 7:9 (ASV)

Strangers have devoured his strength, and he knows it not - Like Samson, when, for sensual pleasure, he had betrayed the source of his strength and God had departed from him, Israel knew not how or in what way his alliances with the pagans had impaired his strength. He regarded his losses at the hand of the enemy as superficial wounds, which time would heal; he did not think of them as tokens of God’s separation from him—that his time of trial was coming to its close, his strength decaying, his end at hand. Israel was not only incorrigible, but past feeling (Ephesians 4:19), as the Apostle says of the pagan.

The marks of wasting and decay were visible to sight and touch; yet he himself did not perceive what all saw except himself. Israel had sought strangers for help, and it “had turned to his decay.” Pul and Tiglath-pileser had devoured his strength, despoiling him of his wealth and treasure, the flower of his men, and the produce of his land, draining him of his riches, and severely oppressing him through the tribute imposed upon him. But “like men quite stupefied, they, though thus continually gnawed upon, yet suffered themselves willingly to be devoured, and seemed insensible of it.” Yet not only so, but the present evils were the forerunners of worse. Grey hairs, themselves the effects of declining age and tokens of decay, are the forerunners of death. “Your grey hairs are your passing-bell,” says the proverb.

The prophet repeats, after each clause, “he knows not.” He knows nothing; he knows not the tokens of decay in himself, but hides them from himself; he knows not God, who is their author; he knows not their cause—his sins; he knows not their end and object—his conversion; he knows not what, since he knows none of these things, will be their outcome: his destruction.

People hide from themselves the tokens of decay, whether of body or soul. And so death, whether of body or soul or both, comes upon them unawares.

“Looking on the surface, he imagines that all things are right with him, not feeling the secret worm that gnaws within. The outward garb remains; the rules of fasting are observed; the stated times of prayer are kept; but the heart is far from Me, saith the Lord.”

“Consider diligently what you love, what you fear, at what you rejoice or are saddened, and you will find, under the habit of religion, a worldly mind; under the rags of conversion, a heart of perversion.”