Sahih Bukhari Volume 2, Book 23, Hadith Number 348.

Narated By Um ‘Atiyya : The daughter of the Prophet expired, and he said to us, “Wash her three or five times, or more if you see it necessary, and when you finish, notify me.” So, (when we finished) we informed him and he unfastened his waist-sheet and told us to shroud her in it.