Musannaf Ibn Abi Shayba 35:211

Ibn ‘Uyaynah narrated to us, from ‘Abdullah ibn Dinar, who said: I went with Ibn ‘Umar to the Banu Mu‘awiyah, and dogs barked at us. He said: The Messenger of Allah (ﷺ) said: "Whoever acquires a dog, except for a hunting dog or a dog for livestock, two qirats of his reward decrease every day."