Musannaf Ibn Abi Shayba 1:792

Abu Bakr narrated to us, he said: Sufyan ibn 'Uyaynah narrated to us, from Ayyub ibn Musa, from Sa'id ibn Abi Sa'id, from 'Abdullah ibn Rafi', from Umm Salamah, she said: I said, "O Messenger of Allah, I am a woman who braids my hair; should I undo it for the bath of major ritual impurity (janabah)?" He said, "It is sufficient for you in that regard to pour three handfuls of water over it, then you pour water over yourself, and you will be purified," or "then you will have become purified."