Surah Ash-Shu'ara, ayah 201

لَا يُؤۡمِنُونَ بِهِۦ حَتَّىٰ يَرَوُاْ ٱلۡعَذَابَ ٱلۡأَلِيمَ ٢٠١

Lā yu'minūna bihī hattā yarawul-'adhābal-alīm

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