Musnad Ahmad 1153:888

'Affan narrated to us, Hammam narrated to us, he said: Hisham ibn 'Urwah informed us, from his father, from 'Aishah, she said: "The Messenger of Allah (peace and blessings of Allah be upon him) was taken [in death] while his head was between my chest and my neck." She said: "Then when his soul departed, I never smelled a scent more pleasant than it."