Musnad Ahmad 1153:552

Abu al-Mughirah narrated to us, he said: al-Awza'i narrated to us, he said: Abu 'Ubayd narrated to me, he said: 'Aishah said: The Messenger of Allah, peace and blessings of Allah be upon him, entered upon me at Sarif while I was menstruating, and I was feeling downcast. He said to me: "Are you menstruating?" I said: "Yes, O Messenger of Allah, and I do not think that women were created except for evil." He said: "No, but it is a thing with which the women of the Children of Adam have been afflicted."