Rezin. Compare Isa 7. He and Pekah are the two firebrands of 2Ki_7:4. The events in verses: 2Ki_16:5-9 are said by some to contradict 2Ch_28:5-20; but the event recorded in 2 Chron. happened the year before, directly after (2Ch_28:5-20), in 631 (see App-50.) Rezin and Pekah both attacked directly after his accession (successfully). But they confederated unsuccessfully, came up. Pekah's design to persuade Ahaz failed; and he tried to supersede him himself ("Tabeal" being a cipher for Remaliah). Compare Isa_7:6.
could not: because of the promise to David. Compare Isa_7:7, Isa_7:16.