Qur'ān 26:201 · Ash-Shu'ara (الشعراء)

لَا يُؤْمِنُونَ بِهِۦ حَتَّىٰ يَرَوُا۟ ٱلْعَذَابَ ٱلْأَلِيمَ

They will not believe in it until they see the painful punishment.