Musnad Ahmad 27:1855

'Abd al-Razzaq narrated to us, Sufyan informed us, from Isma'il ibn Umayyah, from Nafi', from Ibn 'Umar, who said: The Prophet, may Allah bless him and grant him peace, used to send us to the outskirts of Medina, and he would command us not to leave any dog without killing it, until we would even kill the dog belonging to the nomad of the desert.