Musnad Ahmad 430:13

Abu al-Nadr narrated to us, he said: al-Mubarak narrated to us, from al-Hasan, from Abdullah ibn Mughaffal, he said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "Pray in the resting places of sheep, and do not pray in the resting places of camels, for they were created from the devils."