Sahih Muslim
The Book of Transactions (Kitab Al-Buyu)
Book Number: 010 / Hadith Number: 3821
Ibn Umar (Allah be pleased with them) narrated Allah's Messenger (may peace be upon him) as saying: He who kept a dog ther than one meant for watching the fields or herds or hunting would lose one qirat every day out of his reward (with God).