Musnad Ahmad 1153:2217

Sulayman ibn Hayyan narrated to us, from Hajjaj, from Abd al-Rahman ibn al-Aswad, from his father, 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).