Hath sworn. This is the emphatic word—the new thing in the prophecy. God but seldom declares his purposes with an oath—never but in condescension to the weakness of his creatures, who, though they misdoubt his word, can feel the immutability of an oath (Hebrews 6:17), and yield it the credence and the confidence which they refuse to a bare assertion.
As I have thought … as I have purposed. A reference to the prophecies previously given in Isaiah 10:1-34. So shall it come to pass; literally, so it hath been—a striking instance of the "preterite of prophetic certainty."
So shall it stand; literally, as I have purposed, that shall stand.