Musnad Ahmad 581:1

Muhammad ibn Ubayd narrated to us, Muhammad ibn Ishaq narrated to us, from Muhammad ibn Ibrahim, from Umar ibn al-Hakam ibn Thawban, from Abu Las al-Khuza’i, who said: The Messenger of Allah (peace and blessings of Allah be upon him) provided us with mounts from the camels of charity for the Hajj. We said: "O Messenger of Allah, we do not see that these will carry us." He said: "There is no camel but that there is a devil upon its hump, so mention the name of Allah upon them when you mount them, as He has commanded you. Then, utilize them for your own needs, for it is Allah who carries [you]."