Is it permissible for a man to begin the ghusl by physically purifying himself with soap, and then perform the ritual ghusl?

Using shampoo and soap for the ritual bath (ghusl (definition)) is not obligatory; rather, it suffices to pour water over the entire body so that it reaches all its parts. For those who wish to use them, there is no impediment to washing with them first and then performing the ritual bath with water alone. Alternatively, one can intend to perform the ghusl for janabah (definition) with the water used to remove the shampoo and soap, thereby encompassing both matters with the comprehensive application of water. Sheikh Ibn Baz has issued a fatwa (definition) stating that bathing with soap and shampoo suffices for ablution (wudu) if one intends both purifications, though it is preferable to perform wudu first and then ghusl.