Sahih Muslim Book 30, Hadith Number 5849.

Hammam b. Munabbih reported that Abu Huraira reported many ahadith from Allah’s Messenger (may peace be upon him) and one, of them speaks that Allah’s Messenger (may peace be upon him) is reported to have said: Banu Isra’il used to take bath (together) naked and thus saw private parts of one another, but Moses (peace be upon him) used to take bath alone (in privacy), and they said: By Allah, nothing prevents Moses to take bath along with us; but scrotal hernia. One day when he (Moses) was taking bath (alone) he placed his clothes upon a stone, but the stone began to move along with his clothes. Moses raced after it saying: My garment, stone; until (some of the people) of Banu Isra’il looked at the private parts of Moses, and they said: By Allah, there is no trouble with Moses. The stone stopped after he (Moses) had been seen. He took hold of his garments and struck the stone. Abu Huraira said: I swear by Allah that there were six or seven scars on the stone because of the striking of stone by Moses (peace be upon him).