Musnad Ahmad 1153:807

Abu Ahmad narrated to us, he said: Isra'il narrated to us, from Abu Ishaq, from Abu Maysarah, from 'Aishah, she said: "The Prophet, peace and blessings of Allah be upon him, used to touch me while I was menstruating, and he would enter with me into my blanket while I was menstruating, but he was the most capable of you in controlling his desire."