Were they to see a piece of the sky(5078) falling (on them), they would (only) say: "Clouds gathered in heaps!"
5078 In 26:187, Shu'ayb, the Prophet of Allah, is challenged by the Companions of the Wood "to cause a piece of sky to fall on us, if thou art truthful." Such a challenge, in some form or other, is addressed to all Prophets of Allah. It is mere defiance. It has no meaning. If a piece of the sky were to fall on them, it would not convince them, for they would only say: "These are only clouds gathered in heaps." They do not wish to believe. Otherwise there are ample Signs and Evidences of Allah's Plan in Creation and in man's own heart.