Sahih Bukhari
Fighting for the Cause of Allah (Jihaad)
Volume: 004 / Book Number: 052 / Hadith Number: 43
Narrated 'Aisha:
(That she said), "O Allah's Apostle! We consider Jihad as the best deed. Should we not fight in Allah's Cause?" He said, "The best Jihad (for women) is Hajj-Mabrur (i.e. Hajj which is done according to the Prophet's tradition and is accepted by Allah)."