Musnad Ahmad 1153:2307

Ya'qub narrated to us, Ibn Akhi Ibn Shihab narrated to us, and he mentioned part of the hadith of al-Hudaybiyyah. He said: Muhammad ibn Muslim said: Urwah ibn al-Zubayr informed me that Aisha, the wife of the Prophet, may Allah bless him and grant him peace, informed him that the Messenger of Allah, may Allah bless him and grant him peace, used to test those who emigrated to him from the believing women with this verse. Allah the Exalted says: "O Prophet, when the believing women come to you pledging to you that they will not associate anything with Allah, nor will they steal, nor will they commit unlawful sexual intercourse, nor will they kill their children, nor will they bring forth a slander they have invented between their arms and legs, nor will they disobey you in what is right - then accept their pledge and ask forgiveness for them of Allah. Indeed, Allah is Forgiving, Merciful." [Al-Mumtahanah: 12] Urwah ibn al-Zubayr said: Aisha said: Whoever among the believing women acknowledged this condition, the Messenger of Allah, may Allah bless him and grant him peace, would say to her: "I have accepted your pledge by speech." And by Allah, his hand never touched the hand of a woman at all during the pledging. He did not accept their pledge except by his saying: "I have accepted your pledge on that."