Musnad Ahmad 1153:1649

Yahya narrated to us, from Hisham—meaning al-Dastawa'i—who said: Yahya narrated to us, from Abu Salamah, who said: I asked Aisha, "Did the Messenger of Allah, peace and blessings of Allah be upon him, sleep while he was in a state of janabah (major ritual impurity)?" She said: "Yes, but he would perform wudu (ablution) like his wudu for prayer."