﴿ أَوْ تُسْقِطَ ٱلسَّمَآءَ كَمَا زَعَمْتَ عَلَيْنَا كِسَفًا أَوْ تَأْتِىَ بِٱللَّهِ وَٱلْمَلَٰٓئِكَةِ قَبِيلًا ﴾

“or thou cause the skies to fall down upon us in smithereens, as thou hast threatened, or [till] thou bring God and the angels face to face before us,”

or until you cause the heaven to fall upon us as you assert in pieces or bring God and the angels right in front of us face to face with us before our very eyes so that we might see them;