Musnad Ahmad 1153:952

'Abd al-Wahhab narrated to us, he said: Hisham informed us, from Yahya, from Abu Salamah, he said: I asked 'Aishah, "Did the Prophet, peace and blessings of Allah be upon him, sleep while he was in a state of major ritual impurity (junub)?" She said: "Yes, and he would perform ablution like his ablution for prayer."