Musnad Ahmad 1170:5

Waki’ narrated to us, he said: Sufyan narrated to us, from Muhammad ibn al-Munkadir, he said: I heard Umaymah bint Ruqayqah narrating that the Prophet, peace and blessings of Allah be upon him, said: "I do not shake hands with women. My word to one woman is only like my word to one hundred women."