What is the Sunnah way to perform Ghusl according to Sahih Hadiths?

Regarding the method of performing Ghusl (ritual bath) from the Prophet of Allah ﷺ, the narrations of Sayyidah Aisha and Sayyidah Maymunah (RA) recorded by Imam Bukhari and Imam Muslim (RA) hold fundamental importance.

The summary of these narrations is as follows:

1. Making the Intention (Niyyah) for Purification

First and foremost, the intention must be made making the intention for Taharah (ritual purity).

• Hadith: Actions are judged by intentions.
  (Sahih al-Bukhari: 1, Sahih Muslim: 1907)
  

Imam al-Bukhari (RA) narrated this Hadith as the very first narration.
The intention is the resolve of the heart; no specific words are to be uttered with the tongue.
Simply intending in one’s mind, I am performing Ghusl to attain purity, constitutes the intention.

2. Washing Both Hands Two or Three Times

After making the intention, the second step is to wash both hands two or three times.

• Hadith: As mentioned in the narration of Sayyidah Aisha (RA), whenever the Prophet ﷺ took a bath after Janabah (major ritual impurity), he began by washing his hands.
  (Sahih al-Bukhari: 248, Sahih Muslim: 316)
  
  
• Hadith: In the narration of Sayyidah Maymunah (RA), the Prophet of Allah ﷺ poured water with his right hand over his left hand and washed both hands two or three times.
  (Sahih al-Bukhari: 265, Sahih Muslim: 317)

3. Washing Any Impurity on the Body and Performing Istinja Thoroughly

After washing the hands, if there is any visible impurity on the body, it should be washed off, and the private parts should be washed, meaning performing Istinja
(cleansing after relieving oneself) thoroughly.

• Hadith: In the narration from the Prophet of Allah ﷺ by Sayyidah Maymunah RA: Then, after washing both hands, the Prophet of Allah ﷺ washed his private parts.
  (Sahih al-Bukhari: 265, Sahih Muslim: 317)
  

4. Washing Both Hands (With Soap, etc.) and Performing Wudu Like That for Salah

Following this, as the fourth step after performing Istinja, wash both hands with soap
(or clean earth) and perform Wudu (ablution) just as one does for Salah:
After washing the hands, rinse the mouth, sniff water into the nostrils, wash the face,
and wash both arms, including the elbows.

• Hadith: As mentioned in the narration of Sayyidah Aisha (RA)
  He performed Wudu just like the Wudu for Salah.
  (Sahih al-Bukhari: 248, Sahih Muslim: 316)
  
  
• Hadith: And in the narration of Sayyidah Maymunah (RA): After performing Istinja,
  the Prophet of Allah ﷺ struck his hand against the ground or wall two or three times
  [to clean it thoroughly with earth or what corresponds to soap today], then rinsed his mouth, sniffed water into his nostrils, washed his face, and washed both forearms.
  (Sahih al-Bukhari: 265, 279, Sahih Muslim: 317)

5. Pouring Water Over the Right and Left Sides of the Head Instead of Wiping

As the fifth step, instead of wiping (Masah) over the head, take water with both hands and pour it over the right side of the head and then over the left side, running the fingers thoroughly through the hair and rubbing it until the water reaches the roots of the hair.

• Hadith: Sayyidah Aisha (RA) states:
  He ran his fingers through his hair until he was certain that he had moistened his scalp,
  then he poured water over his head three times.
  (Sahih al-Bukhari: 248, Sahih Muslim: 316)
  
  
• Hadith: And in the narration of Sayyidah Maymunah (RA):
  The Prophet of Allah ﷺ poured water over his head and rubbed it thoroughly until the water reached the roots of the hair.
  (Sahih al-Bukhari: 265, Sahih Muslim: 317)

6. Pouring Water Over the Entire Body, First on the Right Side Then on the Left Side

After pouring water over the head, pour water over the entire body first on the right side and then on the left side so that water reaches every part of the body and no spot remains dry.

• Hadith: In the narration of Hazrat Aisha (RA): Then he washed the rest of his body.
  (Sahih al-Bukhari: 248, Sahih Muslim: 316)
  
  
• Hadith: And in the narration of Hazrat Maymunah (RA):
  Then he poured water over his entire body.
  (Sahih al-Bukhari: 265, Sahih Muslim: 317)
  

7. Washing Both Feet at the End

And finally, washing both feet at the end.

• Hadith: In the narration of Sayyidah Maymunah (RA)
  Then he washed both his feet.
  (Sahih al-Bukhari: 265, Sahih Muslim: 317)
  

Summary of the Method:

In summary, the method consists of:

1. Washing both hands first.
2. Washing away any visible physical impurity from the body and performing Istinja.
3. Washing both hands again with soap (or earth) and performing Wudu.
4. When reaching the stage of wiping the head, pouring water thoroughly over the head instead.
5. Pouring water over the entire body—first on the right side, then on the left side.
6. Lastly, wash both feet.

This is the Sunnah method of performing Ghusl as transmitted from the Prophet of Allah ﷺ.