Sahih Bukhari Volume 004, Book 055, Hadith Number 616.
Narated By Abu Huraira : Allah's Apostle said, "(The Prophet) Moses was a shy person and used to cover his body completely because of his extensive shyness. One of the children of Israel hurt him by saying, 'He covers his body in this way only because of some defect in his skin, either leprosy or scrotal hernia, or he has some other defect.' Allah wished to clear Moses of what they said about him, so one day while Moses was in seclusion, he took off his clothes and put them on a stone and started taking a bath. When he had finished the bath, he moved towards his clothes so as to take them, but the stone took his clothes and fled; Moses picked up his stick and ran after the stone saying, 'O stone! Give me my garment!' Till he reached a group of Bani Israel who saw him naked then, and found him the best of what Allah had created, and Allah cleared him of what they had accused him of. The stone stopped there and Moses took and put his garment on and started hitting the stone with his stick. By Allah, the stone still has some traces of the hitting, three, four or five marks. This was what Allah refers to in His Saying: "O you who believe! Be you not like those Who annoyed Moses, But Allah proved his innocence of that which they alleged, And he was honorable In Allah's Sight." (33.69)