Sahih Bukhari
Sahih Bukhari Volume 003, Book 043, Hadith Number 628.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 43. Oppressions
Narated By Ibn 'Abbas : The Prophet sent Mu'adh to Yemen and said, "Be afraid, from the curse of the oppressed as there is no screen between his invocation and Allah."