Sahih al-Bukhari 2274Book 37, Hadith 14
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا عَبْدُ الْوَاحِدِ، حَدَّثَنَا مَعْمَرٌ، عَنِ ابْنِ طَاوُسٍ، عَنْ أَبِيهِ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ نَهَى رَسُولُ اللَّهِ صلى الله عليه وسلم أَنْ يُتَلَقَّى الرُّكْبَانُ، وَلاَ يَبِيعَ حَاضِرٌ لِبَادٍ. قُلْتُ يَا ابْنَ عَبَّاسٍ مَا قَوْلُهُ لاَ يَبِيعُ حَاضِرٌ لِبَادٍ قَالَ لاَ يَكُونُ لَهُ سِمْسَارًا.
Ibn `Abbas said, "The Prophet (ﷺ) forbade the meeting of caravans (on the way) and ordained that no townsman is permitted to sell things on behalf of a bedouin." I asked Ibn `Abbas, "What is the meaning of his saying, 'No townsman is permitted to sell things on behalf of a bedouin.' " He replied, "He should not work as a broker for him."