Mukhtasar Muslim

Abu Huraira (may Allah be pleased with him) reports that the Messenger of Allah (peace and blessings of Allah be upon him) said: Whoever keeps a dog (without necessity), except that it is for herding livestock, hunting, or guarding crops, then (otherwise) a qirat (portion) of his reward will be reduced every day. Zuhri (the narrator) said that Ibn Umar (may Allah be pleased with them both) was informed of Abu Huraira’s statement that he also exempted the dog for guarding crops, so he said: May Allah have mercy on Abu Huraira, he was a man of the fields. (But this narration of Zuhri is disconnected, because in Muslim itself, there is a hadith of Ibn Umar (may Allah be pleased with them both) which allows keeping a dog for guarding crops.)