Al Mulk Ayah 17

أَمْ أَمِنتُم مَّن فِى ٱلسَّمَآءِ أَن يُرْسِلَ عَلَيْكُمْ حَاصِبًا‌ۖ فَسَتَعْلَمُونَ كَيْفَ نَذِيرِ ١٧ Or do you feel secure that the One Who is in heaven will not unleash upon you a storm of stones. Only then would you know how ?serious? My warning was!