Abu Dawud Book 3, Hadith Number 1656.

Narated By AbuHurayrah : I heard the Apostle of Allah (PBUH) as saying something similar to this tradition. He (the narrator) said to AbuHurayrah: What is due on camels? He replied: That you should give the best of your camels (in the path of Allah), that you lend a milch she-camel, you lend your mount for riding, that you lend the stallion for covering, and that you give the milk (to the people) for drinking.