Musnad Ahmad 1153:1566

Yahya narrated to us, from Shu'bah, who said: Al-Hakam narrated to us, from Ibrahim, from Al-Aswad, from Aisha, who said: "When the Messenger of Allah (peace and blessings of Allah be upon him) was in a state of major ritual impurity (janabah) and wanted to sleep, he would perform ablution (wudu)." Waki' and Muhammad ibn Ja'far said in this hadith: "If he wanted to sleep or eat, he would perform ablution." Yahya said: Shu'bah omitted the hadith of Al-Hakam regarding the one in a state of major ritual impurity performing ablution if he wanted to eat.