Sahih Bukhari Volume 9, Book 89, Hadith Number 321.

Narrated By ‘Aisha : The Prophet used to take the Pledge of allegiance from the women by words only after reciting this Holy Verse: (60.12) “…that they will not associate anything in worship with Allah.” (60.12) And the hand of Allah’s Apostle did not touch any woman’s hand except the hand of that woman his right hand possessed. (i.e. his captives or his lady slaves).