الشعراۤء — Asy-Syu'ara' Ayat 201

لَا يُؤْمِنُوْنَ بِهٖ حَتّٰى يَرَوُا الْعَذَابَ الْاَلِيْمَ

Lā yu'minūna bihī ḥattā yarawul-‘ażābal-alīm(a).

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