Kushtaat refers to the act of skinning (eg. an animal) or peeling.
Why would one skin an animal? To get to the meat. To get to that which is hidden beneath the skin.
A question may arise. Are not the heavens completely destroyed when the horn is blown? Why is it here the removing of the heavens has been mentioned after the Resurrection and not before?
Ibn Ashoor said; the heavens will not be completely destroyed rather they will have been torn up having visible gaps in them for all to see but after the accounting has been done then the shy/heavens will be completely removed from its place then the reality of Jannah and Jahannam will be made clear for All to see.
Imaam Al-Biqaai said: in this verse Allah is mentioning the last thing (that will remain) of this wold as we know it (after the Resurrection) and this will be the last preventing factor which will prevent the reality of Jannah and Jahannam from coming close.
Once they are removed (after the accounting and questioning) then the reality of Jannah and Jahannam will be made clear. Which fits in beautifully with the next verses.
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