It was narrated from 'Abdullah bin Mughaffal that the Messenger of Allah said:

"Were it not that dogs form one of the communities (or nations - of creatures), I would have commanded that they be killed. But kill those that are all black. Any people who keep a dog, except for dogs used for farming, hunting or herding livestock, one Qirat will be deducted from their reward each day."

أَخْبَرَنَا عِمْرَانُ بْنُ مُوسَى، قَالَ حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، قَالَ حَدَّثَنَا يُونُسُ، عَنِ الْحَسَنِ، عَنْ عَبْدِ اللَّهِ بْنِ مُغَفَّلٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏

‏ لَوْلاَ أَنَّ الْكِلاَبَ أُمَّةٌ مِنَ الأُمَمِ لأَمَرْتُ بِقَتْلِهَا فَاقْتُلُوا مِنْهَا الأَسْوَدَ الْبَهِيمَ وَأَيُّمَا قَوْمٍ اتَّخَذُوا كَلْبًا لَيْسَ بِكَلْبِ حَرْثٍ أَوْ صَيْدٍ أَوْ مَاشِيَةٍ فَإِنَّهُ يَنْقُصُ مِنْ أَجْرِهِ كُلَّ يَوْمٍ قِيرَاطٌ ‏

‏ ‏.‏