It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) in a marfu’ form that when a dog puts its mouth into the utensil of any one of you, he should wash that utensil seven times.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 7346
Hadith Gradingحکم دارالسلام:إسناده صحيح، والحديث رفعه ثابت دون شك، خ: 172، م: 279.