Tafsir of Al-Mu'minoon 23:113-114

"They will say: 'We remained a day...'"

They considered the duration of their stay in the world short in comparison to their eternity [in the Hereafter] and the torment they are currently enduring. This is because one who is being tested finds the days of their trial long, while viewing the days of ease that passed as short.

Alternatively, it is because they were previously in pleasure, and days of pleasure are short. Or, it is because what has passed is, in effect, as if it never existed. God confirmed their estimation of the brevity of their years in the world and rebuked them for the heedlessness they were in.

It is recited: "So ask the counters" (fas'al al-‘āddīn). The meaning is: We do not know the count of those years except that we deem them short, calculating them as a day or part of a day, due to the torment we are in and our inability to count them. Therefore, ask those who are capable of counting and those who can direct their thoughts toward it.

It is also said: Ask the angels who count the lifespans of the servants and record their deeds.

It is recited: (al-‘ādīn) with a light [single] dāl, meaning: the oppressors, for they say just as we say.

It is recited: (al-‘ādiyyīn), meaning: the ancient ones who lived long lives, for they consider it short; so how much more so for those beneath them?

From Ibn Abbas: The torment they were in between the two trumpet blasts caused them to forget [the duration].

"Did you then think that We had created you in vain, and that you would not be brought back to Us? Exalted be God, the Sovereign, the Truth; there is no god but He, the Lord of the Noble Throne. And whoever invokes another god with God, for which he has no proof, his reckoning is only with his Lord. Indeed, the disbelievers will not succeed. And say: 'My Lord, forgive and have mercy, for You are the best of the merciful.'"