Al-Kahf: (99 - 101) And We left some of them that day...

1. The first is that the day refers to when the barrier (Sadd) was broken, and some of them surged against others after being prevented from exiting.
2. The second is that "that day" refers to the time of their emergence, when they surge against one another. It is narrated that when they emerge from behind the barrier, they surge, crowding the lands. They will come to the sea and drink its water, eat its creatures, then eat the trees, and then eat the flesh of people. They will not be able to approach Mecca, Medina, or Jerusalem. Then, God will send animals against them whose entry into their ears will cause them to die.
3. The third interpretation is that "that day" refers to the Day of Resurrection.

All these interpretations are plausible, but the closest meaning is the time when God made that barrier level (dukkā), at which point some of them surged against others. After that, the Trumpet will be blown, and this event will be among the signs of the Hour. The discussion concerning the Trumpet has preceded and will follow.

As for the unveiling of Hell (Jahannam) so that it becomes exposed with its terrors, this serves as a punishment for the disbelievers, due to the immense distress that will overwhelm them.

The Almighty clarified that He will reveal it to the disbelievers who were blind and deaf:

• Blindness (al-'umā) is what is meant by His saying: "Their eyes were in a covering from My remembrance." This means their intense aversion to accepting the truth.
• Deafness (al-ṣumam) is what is meant by His saying: "And they could not hear." This implies their state was worse than mere deafness, because a deaf person might still be able to hear if someone shouts loudly, whereas these individuals had lost that capacity entirely.

The scholars used the verse "And they could not hear" as evidence that capacity (istita'ah) is tied to the action (al-fi'l), because since they did not hear, they lacked the capacity to hear.

Al-Qadi [Al-Baqillani] stated that it means their aversion to hearing that speech and their finding it burdensome, similar to a man saying, "I cannot bear to look at so-and-so."