Verse 17

أَمْ أَمِنتُم مَّن فِى ٱلسَّمَآءِ أَن يُرْسِلَ عَلَيْكُمْ حَاصِبًا فَسَتَعْلَمُونَ كَيْفَ نَذِيرِ

Or, are you completely sure that the One in the sky would not send a storm upon you so that you will know the consequences of the warnings?