All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, is His slave and Messenger.
It is incumbent on a person in a state of Janaabah (major ritual impurity) due to sexual intercourse or other reasons to wash his whole body with water with the intention of removing the ritual impurity. This is the prescribed Ghusl (ritual bath) for Janaabah. The normal bathing in which one uses soap and water (to clean the body) without the intention of removing the ritual impurity, is not sufficient in terms of clearing one’s liability from the obligation of performing Ghusl for Janaabah and removing the ritual impurity. His prayers afterward would be invalid until he washes his body with water with the intention of performing Ghusl for Janaabah. However, if a person washes his body with soap and then pours water over it with the intention of performing Ghusl for Janaabah with that water, then his Ghusl is valid. The following question was posed to the Permanent Committee for Iftaa’: Can soap be used in the Ghusl for Janaabah, and why?
The Committee’s answer was as follows: “It is obligatory to perform Ghusl for Janaabah with water, and it is not required to use cleaning products such as soap and the like. This is what the reported Sunnah of the Prophet indicated. If soap or similar cleaning products are used, then there is nothing wrong with that.” [End of quote from Fataawa Al-Lajnah Ad-Daa’imah]
Allah Knows best.