Sahih Muslim Book 10, Hadith Number 3828.
Chapter : Riba (Usury).
Sufyan b. Abu Zuhair (he was a person belonging to the tribe of Shanu’a and was amongst the Companions of Allah’s Messenger [may peace be upon him ) said: I heard Messenger of Allah (may peace be upon him) as saying: He who kept a dog (other than that) which is indispensable for watching the field or the animals would lose one qirat out of his deeds every day. As-Sa’ib b Yazid (one of the narrators) said: Did you hear it from Allah’s Messenger (may peace be upon him)? He said: Yes, by the Lord of this mosque.