An-Naba 78:19 - Linguistic Miracle

The heaven was opened to become gateways

Earlier, Allah had said:

وَبَنَيْنَا فَوْقَكُمْ سَبْعًۭا شِدَادًۭا

And created above you seven strong creations?

Remember that Allah had contrasted the seven strong heavens with the soft earth that could be dug and penetrated to plant seeds inside it. The same earth which could then be forced open by the vegetation inside the earth as they appear out of it. Contrasting the heavens with this earth implied its exact opposite, that the sky could not be opened, that it could not be subjugated like the earth. But here, on the day of separation, the tightly bound knots of heaven separate from each other, allowing it to open up, allowing free passage through it like a gateway, just like the earth.