Musnad Ahmad 1153:1664

Waki’ narrated to us, he said: Hisham narrated to us, from his father, from ‘Aishah, who said: "The Prophet, peace and blessings of Allah be upon him, would bring his head near to me while he was *mujawir*—meaning in *i’tikaf* (seclusion in the mosque)—while I was in my chamber, and I would wash it and comb it, while I was menstruating."