أَوْ تُسْقِطَ السَّمَاءَ كَمَا زَعَمْتَ عَلَيْنَا كِسَفًا أَوْ تَأْتِيَ بِاللَّهِ وَالْمَلَائِكَةِ قَبِيلًا
“Or you make the heaven fall upon us in fragments as you have claimed or you bring Allah and the angels before [us].”
This ayah is part of the passage in Surah al-Isra (17:90-93) listing the specific miracles the Quraysh demanded before they would believe -- described at this event.