Why Is 'As-Samaa' in Nasb Form in This Ayah

This is a grammatical concept in Arabic known as ishtighaal — sometimes also called al-maf'ul bihi al-muqaddam. It's actually quite straightforward once you see it. Normally in a sentence, the subject is the most prominent element — the one doing the action. But in this kind of construction, the object of the verb is brought forward to the very front of the sentence and then referred to again as a pronoun afterward.

So instead of saying "Allah raised the sky," the Arabic says "the sky — He raised it." The sky is mentioned first, where you would expect the subject to appear, even though it is an object — and then it appears again as a pronoun. This structure exists in other places in the Quran as well.

The purpose of it is emphasis. It is as if the object is being given so much importance that it deserved to be mentioned twice and placed right where you expect the most prominent element. It forces you to stop. Allah elevated the sky — stop and contemplate the sky. And he does the same thing with the Earth in ayah 10. The language is placing a kind of stress on these miraculous signs of Allah, saying: you are no longer able to just pass by these signs without pausing to contemplate them more deeply. That is the rhetorical function of this grammatical choice.