Musnad Ahmad 1250:3

Ishaq ibn Yusuf al-Azraq narrated to us, he said: Hisham informed us, from Hafsa, from Umm Atiyyah, who said: One of the daughters of the Prophet, peace and blessings of Allah be upon him, passed away. The Messenger of Allah, peace and blessings of Allah be upon him, came to us and said: "Wash her with lotus leaves and wash her an odd number of times—three, five, or more than that if you see fit. And put camphor, or something of camphor, in the final washing. When you have finished, inform me." She said: When we finished, we informed him, peace and blessings of Allah be upon him. He cast his lower garment (izar) to us and said: "Shroud her in it."