Sayyiduna Abdullah bin Amr (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "Whoever keeps a dog that is not for hunting or for (guarding) livestock, one qirat is deducted from that person's reward every day."
Al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains a narrator, al-Nadr bin Abdullah al-Azdi, and he is majhul (unknown).