78:1-3
عَمَّ يَتَسَاءَلُونَ عَنِ النَّبَإِ الْعَظِيمِ الَّذِي هُمْ فِيهِ مُخْتَلِفُونَ
“About what are they asking one another? About the great news – that over which they are in disagreement.”
The surah opens on the Makkan street-level dispute about the Quran's teaching, anchoring the cosmic revelation in the immediate social reality of people arguing about the Day of Judgement.
78:40
إِنَّا أَنذَرْنَاكُمْ عَذَابًا قَرِيبًا يَوْمَ يَنظُرُ الْمَرْءُ مَا قَدَّمَتْ يَدَاهُ وَيَقُولُ الْكَافِرُ يَا لَيْتَنِي كُنتُ تُرَابًا
“Indeed, We have warned you of a near punishment on the Day when a man will observe what his hands have put forth and the disbeliever will say: "Oh, I wish that I were dust!"”
The surah's devastating conclusion – the disbeliever's wish to be reduced to the same dust that animals become, preferring non-existence to the prospect of judgement, captures the ultimate regret of the heedless.