Musnad Ahmad 1153:175

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from Thabit ibn 'Ubayd, from Al-Qasim ibn Muhammad, from 'Aishah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Hand me the prayer mat from the mosque." She said: I said: "I am menstruating." He said: "Indeed, your menstruation is not in your hand."