challenge to truth

فَأَسْقِطْ عَلَيْنَا كِسَفًا مِّنَ ٱلسَّمَآءِ إِن كُنتَ مِنَ ٱلصَّـٰدِقِينَ

So cause to fall upon us fragments of the sky, if you should be of the truthful."