This book is regarding the authenticity of Hadith of the Prophet, as there is baseless propaganda that Hadith were not written in the time of the Prophet, but later on, making them unreliable. This is wrong, as Sa-haba used to write Ahadith and sometimes the Prophet himself used to order them to write. But they trusted their memory more than writing. Official compilation took place later on, when Muslim rulers became aware of the weakness of people's memories and the loss of those individuals' writing. This book provides all these details and makes it clear that Hadith is Wahi (Revelation) and source of Islamic Shariah (Law).