Ruling on rubbing the body with a sponge or loofah when doing ghusl?

In the answer to question no. 93056, we stated that when doing ghusl in the case of janaabah, it is sufficient to ensure that water reaches all of the body, and that rubbing or passing the hands over the body when doing ghusl is not obligatory according to the majority of scholars (may Allah have mercy on them), apart from Maalik and some of the scholars who agreed with him (may Allah have mercy on them). 

An-Nawawi (may Allah 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.

End quote from al-Majmoo‘, 2/215 

Based on that, if a person does ghusl by pouring water over the body and making the water reach every part of the body, this is what is required. If he does more than that, by rubbing his body with a sponge or loofah whilst doing ghusl, there is nothing wrong with that, but it is not obligatory and is not a condition of ghusl being valid, as stated above. 

This ruling only applies in the case of someone who combines pouring water over the body with rubbing it with a sponge and the like whilst doing ghusl. 

But if what is meant in the question is the ruling on only passing the sponge over the body whilst doing ghusl, without pouring water on oneself, and being content with whatever dampness gets onto the body from the sponge, then in this case his ghusl is not valid, unless he squeezes the sponge and water flows from it onto his body. In that case, ghusl as prescribed in Islam is done by means of this water that flows onto the body, not by means of merely passing the sponge over the body, even if it is wet. 

For more information on washing the head and the hair in the case of janaabah, please see the answer to questions no. 27065 and 163816 

And Allah knows best.