حدیث کی اھمیت اور ضرورت

A very good intro book on the important of the Hadiths for a Muslim. The author very succinctly and cogently refutes, many of the allegations and charges of the deniers of the Sunnah of the Messenger of Allah.

the best book about authenticity of hadith if you want to study is ""Sunnat ki aeini hesiat" by molana mododi rehmatullah.