Narrated Abu Huraira:
"The Prophet said, 'The (people of) Bani Israel used to take bath naked looking at each other. The Prophet Moses used to take a bath alone. They said, 'By Allah! Nothing prevents Moses from taking a bath with us except that he has a scrotal hernia.' So once Moses went out to take a bath and put his clothes over a stone and then that stone ran away with his clothes. Moses followed that stone saying, "My clothes, O stone! My clothes, O stone!" till the people of Bani Israel saw him and said, 'By Allah, Moses has got no defect in his body.' Moses took his clothes and began to beat the stone.' " Abu Huraira added, "By Allah! There are still six or seven marks present on the stone from that excessive beating."
(Sahih Bukhari .. Vol.1, No:277)