An-Naba 78:18 - Linguistic Miracle

A Day the horn is breathed into, so you come forth as distinct groups

Allah described it as a day of separation which is evident here as well. People will be separated into different, distinct groups. fawj, was originally used for distinct batches of camels sent to a watering place, one after another.¹⁰ It implies distinct groups and clusters of creatures, not just one unified gathering. Earlier, Allah had said regarding them:

ٱلَّذِى هُمْ فِيهِ مُخْتَلِفُونَ

Regarding what they are in disagreement They will be grouped as per the view they held.

¹⁰ Al-Muʿjam al-Ishtiqāqī al-Muʾaṣṣal li-Alfāẓ al-Qurʾān al-Karīm, vol. 3, p. 1634