The Messenger of Allah ﷺ forbade going out to meet caravans before they reached the market, and he forbade a town-dweller selling on behalf of a desert-dweller.I asked Ibn Abbas, "What does it mean, a town-dweller selling on behalf of a desert-dweller?"He replied, "He should not act as a broker for him."
أخبرنا محمد بن رافع قال أنبأنا عبد الرزاق قال أنبأنا معمر عن ابن طاوس عن أبيه
نهى رسول الله ﷺ أن يتلقى الركبان وأن يبيع حاضر لباد قلت لابن عباس ما قوله حاضر لباد قال لا يكون له سمسار
Muslim narrated it in Al-Buyu, chapter "Prohibition of a Townsman Selling for a Bedouin," Hadith 1521, from the hadith of Abdul-Razzaq. Bukhari narrated it in Al-Buyu, chapter "May a Townsman Sell for a Bedouin Without a Fee?" etc., Hadith 2158, from the hadith of Muamar bin Rashid, with the same wording. It is also in Al-Kubra, Hadith 6091.