Hadith 2160
Narrated Abu Huraira: Allah's Apostle said, "A buyer should not urge a seller to restore a purchase so as to buy it himself, and do not practice Najsh; and a town dweller should not sell goods of a desert dweller."
Hadith 2161
Narrated Anas bin Malik: We were forbidden that a town dweller should sell goods of a desert dweller.