Musnad Ahmad 1153:1796

Isma'il narrated to us, he said: Muhammad ibn 'Amr informed us, from Abu Salamah, who said: I said to 'Aishah: "O Mother, did the Messenger of Allah, peace and blessings of Allah be upon him, sleep while he was in a state of major ritual impurity (junub)?" She said: "Yes, he would not sleep until he washed his private parts and performed his ablution for prayer."