Musnad Abu Ya'la al-Mawsili 150:329

Zakariya ibn Yahya narrated to us, Sharik narrated to us, from Ibn Ishaq, from al-Aswad, from Aisha, she said: I perfumed the Messenger of Allah (peace and blessings of Allah be upon him) for his ihram, and I saw the perfume in the parting of his head after three [days], while he was in the state of ihram.