Musnad Ahmad 32:696

'Abd al-Razzaq narrated to us, Sufyan informed us, from Ayyub, from Abu Qilabah, from Anas: "Some people from 'Ukl came to the Prophet, may Allah bless him and grant him peace, and they found the climate of Medina unsuitable. So, he ordered for them some milch camels, and he ordered them to drink from their urine and their milk."