It is not essential to rub the body when doing wudoo’ or ghusl, according to the majority of scholars. It is sufficient to make sure that the water reaches all parts of the body in the case of ghusl. Maalik (may Allaah have mercy on him) differed with regard to this point. 

Al-Nawawi (may Allaah have mercy on him) said: Our view is that rubbing the parts of the body when doing ghusl and wudoo’ is Sunnah, not obligatory. If he pours water over himself and makes it reach every part without touching it with his hand, or he immerses himself in a large amount of water, or he stands beneath a downspout or in the rain with the intention of doing ghusl, and it reaches his hair and his skin, this is acceptable for wudoo’ and ghusl. This is the view of all the scholars, except Maalik and al-Muzani, who stipulated that rubbing the skin is essential for ghusl and wudoo’ to be valid. 

Our companions quoted as evidence the words of the Prophet (peace and blessings of Allaah be upon him) to Abu Dharr (may Allaah be pleased with him): “When you find water, let it touch your skin,” but he did not tell him to do anything more than that. This is a saheeh hadeeth, and there are many similar reports in the hadeeth. End quote from al-Majmoo’ (2/214).  

Ibn Qudaamah (may Allaah have mercy on him) said: He does not have to pass his hand over his body when doing ghusl or wudoo’, if he is certain or thinks it most likely that the water has reached all of his body. This is the view of al-Hasan, al-Nakha’i, al-Sha’bi, Hammaad, al-Thawri, al-Awzaa’i, al-Shaafa’i, Ishaaq and ashaab al-ra’i. 

Maalik said: It is obligatory for him to pass his hand over whatever he can reach. Something similar was stated by Abu’l-‘Aaliyah. ‘Ata’ said: With regard to the one who is junub pouring water all over himself, that is not sufficient, rather he should do ghusl properly, because Allaah says (interpretation of the meaning): “till you wash your whole body” [al-Nisa’ 4:43], and the word aghtasala (translated here as “wash your whole body”) refers to one who rubs himself. And because ghusl is purification from impurity, it is essential to pass the hands over the body, as in tayammum. 

And there is the report which was narrated by Umm Salamah who said: I said: “O Messenger of Allaah, I have braided hair, do I have to do it every time I do ghusl from janaabah and menstruation?” He (peace and blessings of Allaah be upon him) said to her, “Rather it is sufficient for you to pour water over your head three times, then pour water all over your body, and you will be taahir (pure).” Narrated by Muslim.  

Because it is an obligatory ghusl, it is not essential to pass the hands over the body as in the case of washing off an impure substance. What they have said about ghusl meaning to pass the hand over something is not sound, because the word ghasala is used in Arabic to refer to washing a vessel, even if one does not wipe it with the hand.  And the reason why in tayammum we are commanded to wipe with the hand is because it is purification using dust and it is not possible to make the dust reach the skin without passing the hand over it. End quote from al-Mughni (1/290). 

And Allaah knows best.