Sahih Bukhari Volume 003, Book 039, Hadith Number 518.
Narated By Abu Huraira : The Ansar said to the Prophet "Distribute the date palm trees between us and our emigrant brothers." He replied, "No." The Ansar said (to the emigrants), "Look after the trees (water and watch them) and share the fruits with us." The emigrants said, "We listen and obey."