A very important book in which its author intended to collect forty authentic hadiths on the Messenger, may God bless him and grant him peace, and it was chosen by Imam Al -Nawawi because he saw it containing all the purposes in the origins, branches, jihad and other important things, and he also chose it because he saw that each of them is a great rule of The rules of religion. The book is distinguished by the fact that it did not report the correct hadiths.