While there is nothing inherently wrong with studying Malahim , classical scholars have always warned against excessive obsession with apocalyptic details. Many hadiths in Kitabul Malahim are graded da'if (weak) or gharib (strange) in authenticity. Furthermore, modern extremist groups have manipulated apocalyptic narratives to justify violence. A sincere seeker should verify that any Hindi PDF they download includes:
While the original text is in Arabic, several Urdu and Hindi translations exist, often titled "Kitabul Fitan" "Al-Malahim." Sunan Abu Dawud (Hindi)
Please note that I couldn't verify the availability of a Hindi PDF version of "Kitab-ul-Malahim". If you're interested in reading the book, you may want to try searching for alternative sources or translations.