Charles Ellicott Commentary Isaiah 10:20

"And it shall come to pass in that day, that the remnant of Israel, and they that are escaped of the house of Jacob, shall no more again lean upon him that smote them, but shall lean upon Jehovah, the Holy One of Israel, in truth." — Isaiah 10:20 (ASV)

The remnant of Israel ... —For the remnant of Assyria there is as yet no word of hope. (See, however, Isaiah 19:23.) For that of Israel, the prophet, falling back on the thought embodied in the name Shear-jashub (see Note on Isaiah 7:3), predicts a brighter future.

Shall no more again stay upon him that smote them. —The smiter is the king of Assyria, whose protection Ahaz and his counsellors had sought instead of trusting in the Holy One of Israel. Their experience of the failure of that false policy should lead them to see that faith in God was, after all, the truest wisdom.