It is narrated from Sayyiduna Abdullah bin Amr, may Allah be pleased with him, that the Messenger of Allah, peace and blessings be upon him, said: The distance between the earth and the sky is five hundred years’ journey. Even so, if a stone the size of a large bowl or a skull were dropped from the sky towards the earth, it would reach the earth before nightfall. But if it were dropped from one end of a chain downwards, it would keep descending for forty years before reaching its origin or bottom.