HOW TO BATHE A CHILD H 730 "When they were about to bathe little Lady Zainab, may Allah be pleased with her, the Prophet, praise and peace be upon him, directed them to begin with her right side followed by the parts that are washed in the ablution." R 730 Bukhari and Muslim with a chain up to Umm Atiyyah who related this.
722- وعن أم عطية رضي الله عنها : أنَّ النَّبيَّ صلى الله عليه وآله وسلم قَالَ لهن في غَسْلِ ابْنَتِهِ زَيْنَبَ رضي الله عنها : "ابْدَأنَ بِمَيَامِنِهَا ، وَمَوَاضِعِ الوُضُوءِ مِنْهَا" متفقٌ عَلَيْهِ .