Al-Imām al-Bukhārī - upon whom be mercy - narrates: Musaddad narrated to us; he said: Ismā’īl narrated to us; he said: Khālid narrated to us, from Ḥafṣah bint Sīrīn,
from Umm ‘Aṭiyyah (may Allāh Almighty be content with her), who said: The Prophet ﷺ instructed her regarding giving a bath: “Begin with the right side, and start with the places of ablution (Wudū’) when performing ghusl.”
حدَّثنا مُسَدَّدٌ، قالَ: حدَّثنا إِسْماعِيلُ، قالَ: حدَّثنا خالِدٌ، عن حَفْصَةَ بِنْتِ سِيرِينَ:عن أُمِّ عَطِيَّةَ، قالتْ: قالَ النَّبِيُّ ﷺ لَهُنَّ في غَسْلِ ابْنَتِهِ
ابْدَأْنَ بِمَيامِنِها وَمَواضِعِ الوُضُوءِ مِنْها.
Reference: Sahih Al Bukhari 167