A town dweller should not buy goods for a desert dweller and charge commission as a broker Sahih al-Bukhari 2160
Arabic hadith text
حَدَّثَنَا الْمَكِّيُّ بْنُ إِبْرَاهِيمَ، قَالَ أَخْبَرَنِي ابْنُ جُرَيْجٍ، عَنِ ابْنِ شِهَابٍ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، أَنَّهُ سَمِعَ أَبَا هُرَيْرَةَ ـ رضى الله عنه ـ يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم "لاَ يَبْتَاعُ الْمَرْءُ عَلَى بَيْعِ أَخِيهِ، وَلاَ تَنَاجَشُوا، وَلاَ يَبِعْ حَاضِرٌ لِبَادٍ "
Translation
Narrated Abu Huraira
Allah's Messenger (ﷺ) 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."