Dajjal the False Messiah
Details
The Prophet (ﷺ) not only warned his Ummah against Dajjal; the false Messiah, but stated in detail his colour, height, width, eye-shape, inscriptions on his forehead, his seductions, his method of aberrance, how to escape from his temptations, his current location, and so on. All the details about Dajjal are here in this book.