Musannaf Ibn Abi Shayba 1:1829

Abu Bakr narrated to us, he said: Abu Mu'awiyah narrated to us, from al-A'mash, from Abu Razin, from Abu Hurayrah, he said: I heard the Messenger of Allah, may Allah bless him and grant him peace, saying: "If a dog laps from the vessel of one of you, then let him wash it seven times."