armageddon

Respected scholars of Islam, As-Salamu `alaykum.There is a book that is read by many youth nowadays tells about the Battle of Armageddon. The book includes many related pieces of evidence, among which is a Hadith that Abu Hurairah (may Allah be pleased with him) hid. The book mentions that he said that he had two areas of knowledge; one of them he imparted, while he hid the other. He commented on that saying that if he had imparted the other area of knowledge, he would have been slaughtered (and he pointed to his neck when saying so).The book I am talking about gives the forewarning that life on earth is coming to an end and that Al-Mahdy will soon appear.What is your comment on that book?May Allah give you manifold reward!