Musnad Ahmad 30:3783

Rawh narrated to us, Sa’id and ‘Abd al-Wahhab narrated to us, from Sa’id, from Qatadah, from al-Hasan, from Abu Hurayrah: That the Messenger of Allah (peace and blessings of Allah be upon him) said: "The Children of Israel used to bathe naked, and the Prophet of Allah, Musa, possessed modesty and reserve, so he would cover himself when he bathed. Thus, they slandered him regarding his private parts. He said: While the Prophet of Allah (peace and blessings of Allah be upon him) was bathing one day, he placed his garments upon a rock. The rock moved away, and the Prophet of Allah followed it, striking it with his staff, saying: 'My garment, O stone! My garment, O stone!' until it reached a gathering of the Children of Israel, or he reached the midst of them. It stopped, and the Prophet of Allah took his garments. They looked at him and saw the most beautiful of people in creation and the most balanced in form. The gathering said: 'May Allah fight the liars among the Children of Israel.' This was his exoneration, by which Allah exonerated him."