Isaiah 14:30

While Philistia is utterly destroyed, Israel enjoys perfect security under Jehovah's protection (see Isaiah 14:32).

the firstborn of the poor must be explained as a superlative "the poorest of the poor." But many commentators prefer, by slightly altering the word for "firstborn," to read "in my meadow the poor shall feed" (cf. Isaiah 30:23).

he shall slay In spite of the change of person, the subject is still Jehovah, not the Assyrian. Or the verb might be equivalent to a passive, as in R.V. ("shall be slain").