Musnad Ahmad 695:2

Abu Amir narrated to us, Abdullah bin Ja'far narrated to us, from Umm Bakr, from al-Miswar, who said: A Jew passed by me while I was standing behind the Prophet, may God bless him and grant him peace, and the Prophet, may God bless him and grant him peace, was performing ablution. He said: He said, "Lift or uncover his garment from his back." He said: So I went to lift it. He said: "The Prophet, may God bless him and grant him peace, splashed water onto my face."