Surah An-Naba 78:3

ٱلَّذِى هُمْ فِيهِ مُخْتَلِفُونَ

That over which they are in disagreement.

Translation: Saheeh International

Tafsir

concerning which they are at variance for the believers affirm it while the disbelievers repudiate it.

Excerpt from Tafsir al-Jalalayn, commentary on 78:3, via Quran.com. The reader has the full commentary and 9 more tafsirs.