What is the authenticity of the book "Armageddon, The Last Statement, O Ummah of Islam" and the hadiths mentioned therein, and is the hadith of Abu Hurairah on page 39 about Nasser and Sadat and their wars against the Jews authentic?

The hadiths about the Mahdi are mutawatir ma'nawi (recurrently transmitted in meaning). Ibn al-Qayyim mentioned hadiths about the Mahdi in his book, including that he is from the household of the Prophet, peace and blessings be upon him, his name matches the Prophet's name and his father's name, he will fill the earth with justice, he will rule for seven years, and Jesus will pray behind him.

As for the book "Armageddon" by Amin Muhammad Jamal al-Din, it has observations against it: its reliance on weak and fabricated hadiths and narrations, its reliance on نقل (transmissions) from unknown manuscripts, its specification of the Mahdi's emergence without evidence, its definitive assertion of speculative matters, its reliance on Jewish conjectures, and its arrangement of events without evidence.

The Mahdi will emerge, but no one knows the time of his emergence except Allah. What is required of us is to work for the service of religion.