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 - "strangers" - foreigners: the Syrians under Hazael, in the reign of Jehoahaz, the son of Jehu; and Assyrians, in the reign of Menahem, who paid a thousand talents of silver to be confirmed in the kingdom by Pul, the king of Assyria (2 Kings 13:7; 2 Kings 15:19-20. And Shalmaneser, king of Assyria finally carried Israel away captive, because of the defection of Hoshea, king of Israel, to So, king of Egypt, 2 Kings 17:3-6).
Grey hairs - i:e., symptoms of approaching national dissolution.
Are here and there upon - literally, are sprinkled on him.
Yet he knoweth not - though old age ought to bring with it wisdom, he neither knows of his senile decay, nor has the true knowledge which leads to reformation.