Musnad Ahmad 581:2

Ya'qub narrated to us, my father narrated to us, from Ibn Ishaq, Muhammad ibn Ibrahim ibn al-Harith narrated to me, from 'Umar ibn al-Hakam ibn Thawban—and he was trustworthy—from Abu Las al-Khuza'i, who said: The Messenger of Allah (peace and blessings of Allah be upon him) provided us with mounts for the Hajj from the camels of the Sadaqah (charity), which were weak. We said to him: "O Messenger of Allah, these camels are weak; we fear they will not carry us." The Messenger of Allah (peace and blessings of Allah be upon him) said: "There is no camel but that there is a devil upon its hump. So ride them, and mention the name of Allah upon them as you have been commanded, then utilize them for yourselves, for it is Allah who carries."