The Messenger of Allah ﷺ never touched a woman with his hand. He would only take a pledge from her, and once she had given him her pledge, he would say, "Go, I have accepted your pledge."
ما مس رسول الله ﷺ بيده امرأة قط إلا أن يأخذ عليها فإذا أخذ عليها فأعطته قال: اذهبي فقد بايعتك.
Muslim narrated it in the Book of Governance (1866:89) via Ibn Wahb, who said, "Malik narrated to me, from Ibn Shihab, from Urwa, that Ayesha told him about the pledge of allegiance of women." She said, then she mentioned it.