Musnad Ahmad 1170:3

Ishaq ibn Isa narrated to us, he said: Malik informed us, from Muhammad ibn al-Munkadir, from Umaymah bint Ruqayqah, that she said: I came to the Messenger of Allah, may Allah bless him and grant him peace, among a group of women to pledge allegiance to him. We said: "O Messenger of Allah, we pledge allegiance to you that we will not associate anything with Allah, nor steal, nor commit adultery, nor bring forth a slander that we fabricate between our hands and our feet, nor disobey you in what is good." He said: "In what you are able and capable of." She said: So we said: "Allah and His Messenger are more merciful to us than we are to ourselves. Come, let us pledge allegiance to you, O Messenger of Allah." The Messenger of Allah, may Allah bless him and grant him peace, said: "I do not shake hands with women. My word to a hundred women is like my word to one woman."