Whenever the Messenger of Allah ﷺ performed the ritual bath after major impurity, he would wash his hands, then perform ablution as he would for prayer, then begin the bath. He would run his fingers through his hair, and once he was certain that the water had reached his scalp, he would pour water over his head three times, then wash the rest of his body.
حدثنا عبدان قال أخبرنا عبد الله قال أخبرنا هشام بن عروة عن أبيه
كان رسول الله ﷺ إذا اغتسل من الجنابة غسل يديه وتوضأ وضوءه للصلاة ثم اغتسل ثم يخلل بيده شعره حتى إذا ظن أنه قد أروى بشرته أفاض عليه الماء ثلاث مرات ثم غسل سائر جسده