Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) said: "No town-dweller should sell for a desert-dweller." The narrator says: I said: (What is meant by) a town-dweller should not sell for a desert-dweller? He said: It means that he should not become his broker.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10902