Musnad Ahmad 948:1

Hammad ibn Khalid narrated to us, Malik narrated to us, from Yazid ibn Khusayfah, from al-Sa’ib ibn Yazid, from Sufyan ibn Abi Zuhayr, from the Prophet, may God bless him and grant him peace, that he said: "Whoever acquires a dog that does not serve the purpose of guarding crops or livestock, a qirat of his deeds will be deducted every day." Al-Sa’ib said: So I said to Sufyan, "Did you hear this from the Messenger of God, may God bless him and grant him peace?" He said, "Yes, and by the Lord of this mosque."