It was narrated that Abu Razin said:
'I saw Abu Hurairah hitting his forehead with his hand and saying: "O people of Iraq! Do you claim that I would tell a lie against the Messenger of Allah so that it may be more convenient for you and a sin upon me?' I bear witness that I heard the Messenger of Allah say: 'If a dog licks the vessel of anyone of you, let him wash it seven times.'"
English reference: Vol. 1, Book 1, Hadith 363
Arabic reference: Book 1, Hadith 393