Musnad Ahmad 1153:2110

'Abd al-Samad narrated to us, Malik—meaning Ibn Mighwal—narrated to us, he said: I asked 'Abd al-Rahman ibn al-Aswad about perfume for the one in the state of ihram. He said: My father, al-Aswad, informed me, from 'Aishah, that she said: "It is as if I am looking at the glistening of the perfume in the parting of the hair of the Messenger of Allah, peace and blessings of Allah be upon him, while he was in the state of ihram."