وَفُتِحَتِ السَّماءُ فَكانَت أَبوابًا
And the sky will be opened and become gates.
EXEGESIS
The verbs in this verse and the next are actually in the past tense, just like the one in verse 17. There are a few possible explanations for this usage: 1. It could be a way of talking about a future event that will certainly happen, as mentioned earlier. 2. These verbs add to you will come in groups (verse 18), which is a description of a future event. In other words, these two verses serve as an adverb for the previous verse: you will come on that day, while the sky has been opened and the mountains have been set moving. In this case, these two verses could refer to events that happen prior to resurrection, for example upon the first blow of the trumpet.
One may question: how can the sky become gates? Here are a few possible explanations for this: 1. This is a way of emphasising and exaggerating the number of gates that will open in the sky on that day, and it will be as if the entire sky is gates. It is like when a courageous person is described as a lion for emphasis, instead of ‘he is like a lion’. 2. The verse involves an omission: [the parts that open] will become gates. Another possible omission is: the sky will become [something that possesses] gates (dhātu abwāb). 3. The verb open (fataḥa) sometimes describes the accessibility of something. For example, it is used to talk about a path or bridge being opened and accessible to cross. This sense of the term complies with likening the sky to gates, in that sky here refers to certain realities or realms of existence that are hidden from us in this world, but will be opened to us upon the resurrection.
EXPOSITION
There are a few possibilities for what is meant by the opening of the sky: 1. It refers to the disintegration of the current order and state of affairs in the universe, where there is no flaw or crack in the heavens (50:6, 67:3). This is confirmed by many other verses that talk about the cracking or splitting of the sky (55:37, 69:16, 77:9, 81:11, 82:1, 84:1). 2. It concerns the spiritual sky, as seen in some other verses in the Quran (7:40, 15:14, 17:95, 31:5, 51:22). In other words, what veils us from the higher realms and the unseen world will be lifted. The seven tracks that are created above us (23:17) but are concealed from the people will be revealed to them. This second meaning is more apparent given the wording of the verse and that of other similar verses, although both events will happen on that day: The day when the sky with its clouds will split open, and the angels will be sent down [in a majestic] descent (25:25).
Elsewhere the Quran says: Indeed, those who deny Our signs and are disdainful of them – the gates of the heaven will not be opened for them, nor shall they enter paradise (7:40). The apparent contradiction between this verse and the current verse can be solved in a few ways: 1. The two verses concern two different events. The current verse is about the occurrence of resurrection, but verse 7:40 is about a subsequent stage of receiving reward. This is confirmed by the addition of nor shall they enter paradise. 2. The verb opened in verse 7:40 is in an exaggerated from (tufattaḥu), which could indicate either voluntary opening, or the opening of many gates. Therefore, some of the gates of heaven will open to the deniers, but not all of them, or perhaps not voluntarily and in a welcoming way. This meaning complements the first, but is against the same exaggerated form of the verb ‘open’ in several recitations of the current verse.
[1] Alusi, 15/212-213.
[2] Tabari, 30/7.
[3] Razi, 31/13.
[4] Alusi, 15/212.
[5] Alusi, 15/212.
[6] Razi, 31/13, with some elaboration.