Hadith: On taking a ritual bath, the Prophet (may Allah's peace and blessings be upon him) used to wash his hands, then perform ablution like that for prayer, then wash himself

عن عائشة رضي الله عنها قالت: (كان النبي صلى الله عليه وسلم إذا اغْتَسَلَ من الجَنَابَة غَسَل يديه، ثُمَّ تَوَضَّأ وُضُوءَه للصَّلاة، ثمَّ اغْتَسَل، ثُمَّ يُخَلِّلُ بِيَدَيه شعره، حتى إِذَا ظَنَّ أنَّه قد أَرْوَى بَشَرَتَهُ، أَفَاض عليه الماء ثَلاثَ مرَّات، ثمَّ غَسَل سائر جسده. وكانت تقول: كُنت أغتسِل أنا ورسول الله صلى الله عليه وسلم من إِنَاء واحِد، نَغْتَرِف مِنه جَمِيعًا).
[صحيح] - [متفق عليه]

‘Ā'ishah (may Allah be pleased with her) reported: On taking a ritual bath, the Prophet (may Allah's peace and blessings be upon him) used to wash his hands, then perform ablution like that for prayer, then wash himself. He would then run his fingers through his hair until he would feel that the whole skin of his head had become wet. Then he would pour water thrice over his head, and then wash the rest of his body. ‘Ā'ishah further said: "The Messenger of Allah (may Allah's peace and blessings be upon him) and I used to bathe from a single container from which we used to take water simultaneously.”
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

‘Ā'ishah (may Allah be pleased with her) described the way the Prophet (may Allah's peace and blessings be upon him) used to take a ritual bath. He would start with washing his hands so that they would be clean for taking water. He would then perform ablution similar to that for prayer. Since he had thick hair, he used to run his fingers through it, and when the water reached his hair roots, he would then pour water over his head thrice, and then wash the rest of his body. Despite this complete bath, only one water container used to be sufficient for him along with ‘Ā'ishah, and they both used to take water therefrom simultaneously.