Sahih Bukhari
Sahih Bukhari Volume 004, Book 052, Hadith Number 128.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 52. Fighting for the Cause of Allah (Jihaad)
Narated By 'Aisha : The mother of the faithful believers: The Prophet was asked by his wives about the Jihad and he replied, "The best Jihad (for you) is (the performance of) Hajj."