What is the meaning of His, the Almighty's, saying: "And the heaven was opened, and became as gates"?

The meaning of "وَفُتِحَتِ السَّمَاء فَكَانَتْ أَبْوَابًا" (and the heaven was opened and became as gates) is that it will crack open to become like gates, either for the descent of angels, or for its scattering and dissolution. It is also said that every servant has two gates in heaven for their deeds and sustenance, and these will open on the Day of Judgment. This opening is one of the manifestations of the sky cracking on the Day of Judgment, as mentioned in other verses such as: "فَإِذَا انشَقَّتِ السَّمَاء فَكَانَتْ وَرْدَةً كَالِدِّهَانِ" (And when the heaven is split asunder, and becomes rosy like red hide), and "وَانشَقَّتِ السَّمَاء فَهِيَ يَوْمَئِذٍ وَاهِيَةٌ" (And the heaven is split asunder, so it is frail on that Day), and "إِذَا السَّمَاء انشَقَّتْ" (When the heaven is split asunder), and "وَإِذَا السَّمَاء فُرِجَتْ" (And when the heaven is rent asunder), and "إِذَا السَّمَاء انفَطَرَتْ" (When the heaven is cleft asunder).