Terrence Daniels — Edited
Claude, it is a substantive. Basically a word or group of words that commonly are considered nominative when taken together. Jealous (humble opinion, zealous is a better English word here) is adjectival, but with the construction, it functions as nominal. The verse is a bicolon, symmetrical and chiastic where the verb and indirect object sandwich the direct object and adjective. It is a very strong emphatic construction. YHWH Tzavot is going to bring down an extraordinary amount of pain on those who hurt Zion because even his zeal is zealous. Again, my humble opinion but it is based on a bit of academic research.- Sorry, Claude, I was thinking about something completely different, in my posts earlier to your question.