Isaiah 31:9

he shall pass overto his strong hold The clause is difficult. R.V. and A.V. marg. take "his Rock" as subj., "Rock" being a figurative designation either of the king of Assyria or its national deity. This view has nothing to commend it. The A.V. gives a good sense, but a better translation perhaps is: "he shall overpass his rock(-refuge) from terror," the image being that of a hunted animal, which misses its accustomed hiding-place in its fright.

his princes shall be afraid of the ensign This rendering might be explained by ch. Isaiah 18:3: the Assyrian officers shall be affrighted at the signal which Jehovah sets up. A better rendering, however, is: his officers shall be frighted away from the standard, i.e. "even the officers shall desert the standard in panic" (a pregnant construction).

whose fire is … Jerusalem Better: who hath a fire in Zion and a furnace (lit. "oven") in Jerusalem. There is perhaps an allusion here to the meaning of "Ariel" in ch. Isaiah 29:1 ff. The expressions symbolise the two aspects of Jehovah's presence in Zion, light to His friends and destruction to His enemies (as Exodus 14:20). The "oven" is an emblem of the Divine anger in Psalms 21:9; perhaps also in Genesis 15:17.