أَوْ تُسْقِطَ السَّمَاءَ كَمَا زَعَمْتَ عَلَيْنَا كِسَفًا أَوْ تَأْتِيَ بِاللَّهِ وَالْمَلَائِكَةِ قَبِيلًا

Or until you cause the sky to fall in fragments upon us, just as you have averred. Or until you bring Allah and the angels [right] in front of us.