Narrated Ibn Mughaffal: The Messenger of Allaah (sal Allaahu alayhi wa sallam) ordered the killing of the dogs, and then said: Why are they (people) after them (dogs)? and then granted permission (to keep) for hunting and for (the security) of the herd, and said : When the dog licks the utensil wash it seven times, and rub it with earth the eighth time. Abu Dawud said : Ibn Mughaffal narrated in a similar way.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَحْمَدُ بْنُ مُحَمَّدِ بْنِ حَنْبَلٍ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ شُعْبَةَ، حَدَّثَنَا أَبُو التَّيَّاحِ، عَنْ مُطَرِّفٍ، عَنِ ابْنِ مُغَفَّلٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم أَمَرَ بِقَتْلِ الْكِلاَبِ ثُمَّ قَالَ " مَا لَهُمْ وَلَهَا " . فَرَخَّصَ فِي كَلْبِ الصَّيْدِ وَفِي كَلْبِ الْغَنَمِ وَقَالَ " إِذَا وَلَغَ الْكَلْبُ فِي الإِنَاءِ فَاغْسِلُوهُ سَبْعَ مِرَارٍ وَالثَّامِنَةُ عَفِّرُوهُ بِالتُّرَابِ " . قَالَ أَبُو دَاوُدَ وَهَكَذَا قَالَ ابْنُ مُغَفَّلٍ .
sunnah.com