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.'"
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا أَبُو مُعَاوِيَةَ، عَنِ الأَعْمَشِ، عَنْ أَبِي رَزِينٍ، قَالَ رَأَيْتُ أَبَا هُرَيْرَةَ يَضْرِبُ جَبْهَتَهُ بِيَدِهِ وَيَقُولُ يَا أَهْلَ الْعِرَاقِ أَنْتُمْ تَزْعُمُونَ أَنِّي أَكْذِبُ عَلَى رَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ لِيَكُونَ لَكُمُ الْمَهْنَأُ وَعَلَىَّ الإِثْمُ أَشْهَدُ لَسَمِعْتُ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ يَقُولُ " إِذَا وَلَغَ الْكَلْبُ فِي إِنَاءِ أَحَدِكُمْ فَلْيَغْسِلْهُ سَبْعَ مَرَّاتٍ " .
IbnMaja
The Book of Purification and its Sunnah • Hadith 363