Sayyidah Aishah (may Allah be pleased with her) said that the Prophet (peace and blessings be upon him) used to take the pledge from women on the things that Allah Almighty has stated in this verse: "O Prophet, when the believing women come to you pledging to you that they will not associate anything with Allah, nor steal, nor commit adultery, nor kill their children, nor bring forth a slander they have invented between their hands and their feet, nor disobey you in what is right, then accept their pledge and ask Allah's forgiveness for them. Indeed, Allah is Forgiving, Merciful." [Surah al-Mumtahanah: 12] And Sayyidah Aishah (may Allah be pleased with her) said that he (peace and blessings be upon him) never touched the hand of any woman (who was not his own).
This is the wording of the narration of Ali (bin Abdullah al-Madini); in the narration of Ahmad (it says that) the Messenger of Allah (peace and blessings be upon him) used to take the pledge from women by speech, with this verse.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16566