"Say, have you considered: if the punishment of Allah should come to you suddenly"—meaning: at night—"or openly"—meaning: during the day—"will any be destroyed except the wrongdoing people?" He is threatening them with the punishment if they do not believe.
﴿قُلْ أَرَأَيْتَكُمْ إِنْ أَتَاكُمْ عَذَابُ الله بَغْتَة﴾ أَي: لَيْلًا ﴿أَو جهرة﴾ نَهَارًا ﴿هَلْ يُهْلَكُ إِلا الْقَوْمُ الظَّالِمُونَ﴾ يُخَوِّفُهُمُ الْعَذَابَ؛ إِنْ لَمْ يُؤْمِنُوا.
