Musnad Ahmad 1153:271

Yahya narrated to us, from Sufyan, who said: Mansur narrated to us, from Ibrahim, from al-Aswad, from Aisha, who said: "He used to command me, so I would wrap a lower garment (izar) while I was menstruating, then he would touch me. And I used to wash his head while he was in I'tikaf, and I was menstruating."