Tafsir of Ad-Dukhan 44:40

"Indeed, the Day of Judgement" (meaning the separation of truth from falsehood, and the righteous from the perpetrator of falsehood, through recompense; or the separation of a person from their loved ones and relatives) "is their appointed time" (the time of their promise) "altogether."

And it was recited as "miqatahum" (their appointed time) in the accusative case, as the noun of inna, with the predicate being "yawma al-fasl" (the Day of Judgement)—meaning: indeed, the appointed time of their reckoning and recompense is on the Day of Judgement, and it is not like the [ungrammatical] phrase "inna harrasana asadan" (Indeed, our guards are lions).