Ibn 'Umar reported Messenger of Allah ﷺ as saying He who kept a dog other than one meant for hunting or for watching the herd lost out of his deeds (equal to) two qirat every day. (Using translation from Muslim 1574c)  

قَالَ رَسُولُ اللَّهِ ﷺ «مَنْ اقْتَنَى كَلْبًا إِلَّا كَلْبَ صَيْدٍ أَوْ مَاشِيَةٍ نَقَصَ مِنْ عَمَلِهِ كُلَّ يَوْمٍ قِيرَاطَانِ»  

“I heard the Prophet ﷺ say: ‘Whoever keeps a dog that he does not need for farming or herding, one Qirat will be deducted from his (good) deeds each day.’” (Using translation from Ibn Mājah 3206)   

سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ «مَنْ اقْتَنَى كَلْبًا لَا يُغْنِي عَنْهُ زَرْعًا وَلَا ضَرْعًا نَقَصَ مِنْ عَمَلِهِ كُلَّ يَوْمٍ قِيرَاطٌ» قَالُوا أَنْتَ سَمِعْتَ هَذَا مِنْ رَسُولِ اللَّهِ ﷺ؟ قَالَ إِي وَرَبِّ هَذَا الْمَسْجِدِ  

[Machine] The Prophet ﷺ ordered the killing of dogs, then he said, "What is the matter with me and the dogs?" Then he permitted the keeping of farm dogs and hunting dogs.  

أَنَّ النَّبِيَّ ﷺ أَمَرَ بِقَتْلِ الْكِلَابِ ثُمَّ قَالَ «مَالِي وَلِلْكِلَابِ؟» ثُمَّ رَخَّصَ فِي كَلْبِ الزَّرْعِ وَكَلْبِ الصَّيْدِ