Surah Ash-Shu'ara 26:201
لَا يُؤْمِنُونَ بِهِۦ حَتَّىٰ يَرَوُا۟ ٱلْعَذَابَ ٱلْأَلِيمَ
They will not believe in it until they see the painful punishment.
Translation: Saheeh International
Tafsir
They will not believe in it until they behold the painful chastisement
Excerpt from Tafsir al-Jalalayn, commentary on 26:201, via Quran.com. The reader has the full commentary and 9 more tafsirs.