Sahih Bukhari Volume 004, Book 052, Hadith Number 043.

Narated By '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)."