مختصر صحيح بخاري
Mukhtasar Sahih Bukhari
Book of Agriculture
Keeping a dog for guarding crops.
Narrated Abu Huraira (may Allah be pleased with him): The Prophet (peace and blessings of Allah be upon him) said: "Whoever keeps a dog, his reward will decrease by one Qirat every day, except for a dog kept for farming or for guarding livestock."