Musnad Ahmad 1153:2066

Hujayn ibn al-Muthanna narrated to us, he said: Isra'il narrated to us, from Abu Ishaq, from al-Bahiy, from Ibn Umar, from Aisha, from the Prophet, may God bless him and grant him peace, that he said to her: "Hand me the prayer mat from the mosque." She said: "I am menstruating." He said: "Indeed, your menstruation is not in your hand."