Sahih al-Bukhari 172
Sahih al-Bukhari · Book 4: Ablutions (Wudu') · If a dog drinks from the utensil of any one of you then it is essential to wash it seven times
Narrated Abu Huraira:
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ ، عَنْ مَالِكٍ ، عَنْ أَبِي الزِّنَادِ ، عَنِ الأَعْرَجِ ، عَنْ أَبِي هُرَيْرَةَ ، قَالَ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا شَرِبَ الْكَلْبُ فِي إِنَاءِ أَحَدِكُمْ فَلْيَغْسِلْهُ سَبْعًا " .
Allah's Messenger (ﷺ) said, "If a dog drinks from the utensil of anyone of you it is essential to wash it seven times."