Musnad Ahmad 1153:700

Hassan narrated to us, Ibn Lahi'ah narrated to us, he said: Abu al-Aswad narrated to us, from Urwah ibn al-Zubayr, from Aisha: "That the Messenger of Allah, peace and blessings of Allah be upon him, used to sleep while he was in a state of janabah (major ritual impurity) if he performed his ablution for prayer."