Musnad Ahmad 1153:1985

Yazid narrated to us, he said: Muhammad informed us, from Abu Salamah, who said: I asked Aisha, "Did the Messenger of Allah, may Allah bless him and grant him peace, sleep while he was in a state of major ritual impurity (junub)?" She said: "Yes, but he would not sleep until he washed his private parts and performed his ablution for prayer."