Musnad Ahmad 1153:2242

Ishaq ibn Isa narrated to us, he said: Malik narrated to me, from al-Zuhri, from Urwah ibn al-Zubayr, from Amrah, from Aisha, she said: "The Messenger of Allah, peace and blessings of Allah be upon him, would bring his head near to me, and I would comb his hair while I was menstruating, and he was in I'tikaf (seclusion in the mosque). And he would not enter the house except for human necessity."