Musnad Ahmad 1153:2147

Yahya ibn Adam narrated to us, he said: Sharik narrated to us, from Khusayf, he said: A man narrated to me, thirty years ago, from Aisha, she said: "I perfumed my hair intensely with incense, and the Messenger of Allah, peace and blessings of Allah be upon him, said to me: 'O Aisha, do you not know that upon every hair there is a state of ritual impurity (janabah)?'"