The Messenger of Allah ﷺ said regarding the washing of his daughter, "Begin with her right side and with the parts washed in ablution."
قال رسول الله ﷺ في غسل ابنته: ابدأن بميامنها، ومواضع الوضوء منها.
Bukhari narrated it in the Book of Funerals (1255), and Muslim narrated it in the Book of Funerals (43/939), both from the hadith of Ismail bin Ibrahim, who said, Khalid Haddan narrated to us, from Hafsa bint Sirin, from Umm Atiya, and he mentioned it.