Tafsir of Al-Hijr 15:33

(He said) — an initiation of speech similar to what has preceded — (I am not one to prostrate) — the lam is for the emphasis of negation; meaning: it contradicts my state and is not fitting for me to prostrate (to a human) — a dense, physical body (whom You created from ringing clay, from mud shaped into form).

(33) — A summary indication of his claim of superiority and the nobility of his substance. It has been narrated from him — may Allah the Exalted curse him — that he explicitly stated this in another verse. The accursed one intended by this description to explain the extreme baseness of the origin of the one to whom he was commanded to prostrate — though he is far removed from that. He sufficed in other places by recounting some of what he alleged to be a cause for baseness, and in his deviation from tailoring his answer to the question, he sought to evade the disputation, but how could he attain that? It is as if it were said: "I did not abstain from joining the ranks of the prostrators, but rather from that which does not befit my status: prostrating to one of lower merit."

The accursed one erred in thinking that all merit is relative to the material substance. He did not know that merit can be relative to the agent, the form, or the purpose. In fact, the criterion for merit and perfection is the purging of base qualities and the adorning oneself with divine knowledge:

A left hand, yet in it is a cup, and a right hand, yet there is no cup in it, it is a left.

And how excellent is he who said:

Learn who you wish to be, and acquire manners; its substance will enrich you more than your lineage. The true youth is he who says, "Here I am," Not the youth who says, "My father was such and such."

Furthermore, there is an obvious refutation regarding his claim of the superiority of fire over soil, and the discussion concerning that has already preceded.