The Book of Purification and its Sunnah
1/31. Chapter:
Washing a vessel that has been licked by a dog
Sunan Ibn Majah
حَدَّثَنَا مُحَمَّدُ بْنُ يَحْيَى، حَدَّثَنَا ابْنُ أَبِي مَرْيَمَ، أَنْبَأَنَا عَبْدُ اللَّهِ بْنُ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " إِذَا وَلَغَ الْكَلْبُ فِي إِنَاءِ أَحَدِكُمْ فَلْيَغْسِلْهُ سَبْعَ مَرَّاتٍ " .
It was narrated that Ibn 'Umar said: "The Messenger of Allah said: 'If a dog licks the vessel of anyone of you, let him wash it seven times.'"
Reference : Sunan Ibn Majah 366In-book reference : Book 1, Hadith 100English translation : Vol. 1, Book 1, Hadith 366