Is it obligatory to rub the hidden areas of the body, such as the navel, armpit, between the fingers, and the anus, during ghusl, or is merely the water reaching them sufficient for the ghusl to be valid, and is the swift ghusl of people valid?

Whispering (waswasah) is one of the most evil ailments that corrupt a person's religion and worldly life. Its cure is to turn away from it and pay no attention to it. Ghusl (ritual bath) is the pouring of water over the body. According to the preponderant opinion, scrubbing is not obligatory in it. It is sufficient to achieve certainty or a strong presumption that the water has reached all parts of the body. Five minutes or less is enough for the obligatory ghusl. A strong presumption is sufficient for thoroughness, meaning the water reaching all of the skin.