Umm 'Atiyyah (May Allah be pleased with her) reported:
The Prophet (ﷺ) instructed us at the time of washing the dead body of his daughter Zainab (May Allah be pleased with her) to begin with her right side, and from the parts that are washed in Wudu'.[Al-Bukhari and Muslim].
App reference: Book 2, Hadith 43
Arabic/English book reference: Book 2, Hadith 723