‘A’isha said regarding the oath of allegiance taken from women that God’s Messenger used to test them with this verse, “O Prophet, when believing women come to you to swear allegiance to you...” (Al-Qur’an; 60:12). When one of them acknowledged this condition he said to her, “I have made a covenant with you,” doing this only by words which he spoke to her. His hand never touched a woman’s hand when an oath of allegiance was taken.
(Bukhari and Muslim.)