When the Messenger of Allah ﷺ performed the ritual bath after major impurity, he would call for a vessel resembling a milking pail. He would take some water in his palms and begin with the right side of his head, then the left, then he would take water in both palms and pour it over his head.
حدثنا محمد بن المثنى حدثنا أبو عاصم عن حنظلة عن القاسم
كان رسول الله ﷺ إذا اغتسل من الجنابة دعا بشيء من نحو الحلاب فأخذ بكفيه فبدأ بشق رأسه الأيمن ثم الأيسر ثم أخذ بكفيه فقال بهما على رأسه
Bukhari narrated it in the Book of ghusl, chapter on one who begins with a hair-washing preparation or perfume during ghusl, hadith no. 258, and Muslim narrated it in the Book of Menstruation, chapter on the description of the ghusl for janaba, hadith no. 318, both of them from Muhammad bin Muthanna through this chain.