Musnad Ahmad 435:100

Abu Nu'aym narrated to us, he said: 'Abdullah ibn Mubashir, the freed slave of Umm Habibah, narrated to us, from Zayd ibn Abi 'Attab, from Mu'awiyah, he said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Any woman who inserts into her hair the hair of another, she is only inserting it as a falsehood."