Tafsir of As-Saffat 37:95

(He said) — after they had brought him, peace be upon him, and the dialogue had taken place in a manner of reproach and denial toward them: "Do you worship what you carve?"

(That is, that which you carve from idols. "Ma" [what] is a relative pronoun, and its referent [the pronoun which would link it back to the verb] is omitted, which is the apparent and obvious meaning. It has also been suggested that it is an infinitive "ma" [ma masdariyyah], meaning: "Do you worship your carving?" Their reproach for worshipping the act of carving—despite the fact that they worship the idols themselves, which are not the carving itself—is intended to indicate that, in reality, they only worshipped the carving; for before that, the idols were merely stones, and they did not worship them. They only worshipped them after they had carved them. Therefore, in truth, they worshipped nothing but their own carving, and in this [interpretation] there is what there is [of room for discussion].)