It was narrated from 'Aishah that:
The Prophet said to her, when she was menstruating: "Undo your braids and bathe." (Sahih)(A narrator) 'Ali said in his narration: "Undo your head." (IT)
English reference (IT): Vol. 1, Book 1, Hadith 641 (IT)
Arabic reference (IT): Book 1, Hadith 684 (IT)