Musnad Ahmad 1153:937

Muhammad ibn Ja'far narrated to us, he said: Shu'bah narrated to us, from al-Miqdam ibn Shurayh ibn Hani', from his father, who said: 'A'ishah said: "I would gnaw on a piece of meat while I was menstruating, then the Messenger of Allah (peace and blessings of Allah be upon him) would take it and place his mouth where my mouth had been. And I would drink from the vessel, then the Messenger of Allah (peace and blessings of Allah be upon him) would take it and place his mouth where my mouth had been, while I was menstruating."