An-Naba 78:17 - Linguistic Miracle

Indeed, the Day of separation, was the appointed time

The previous verses described things as pairs, man with woman, earth with heaven, and the day with night. It mentioned gardens that were intertwined because everything that led to it, was itself intertwined with each other. Allah now mentions a day that will cause separation, that separates these pairs from each other. The day of separation was the appointed time for the stoppage and breakage of this relationship.

The coming verses will describe this separation. You will see how Allah will describe the breaking apart of the same things He has mentioned thus far in this surah.