Hosea 7:9
Strangers have devoured his strength, and he knoweth it not: yea, gray hairs are here and there upon him, yet he knoweth not. Strangers have devoured his strength, and he knoweth it not: yea, gray hairs are here and there upon him, yet he knoweth not.
Ephraim in the verse is the apostate ten tribes of Israel. Strangers devouring his strength means his power was being consumed by foreign nations, as he mixed himself with other peoples. That loss of strength took place without his recognizing it.
The gray hairs scattered here and there upon him picture his decline and approaching ruin. That sign of decay likewise went unnoticed by him. He could not discern the disastrous outcome of his evil course, and he was soon to become a wanderer among the nations. In this the verse warns that conformity to the world drains spiritual strength and leaves people unaware of their spiritual decline.