Volume 2 · Book 23 · Hadith 350
Narrated Hafsa bint Sirin: Um 'Atiyya said that they had entwined the hair of the daughter of Allah's Apostle in three braids. They first undid her hair, washed and then entwined it in three braids."
— Sahih Bukhari, Volume 2, Book 23: Funerals (Al-Janaa'iz), Hadith #350