صحيح البخاري Sahih Bukhari كتاب البيوع The Book of Sales (Bargains)
بَابُ هَلْ يَبِيعُ حَاضِرٌ لِبَادٍ بِغَيْرِ أَجْرٍ وَهَلْ يُعِينُهُ أَوْ يَنْصَحُهُ:

(68) Chapter. Is it permissible for a person from the town to sell the goods of a desert dweller without taking commission? Should he he help him or try to advise him?

2 hadith
Hadith 2157
حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ ، حَدَّثَنَا سُفْيَانُ ، عَنْ إِسْمَاعِيلَ ، عَنْ قَيْسٍ ، سَمِعْتُ جَرِيرًا رَضِيَ اللَّهُ عَنْهُ ، يَقُولُ : " بَايَعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَلَى شَهَادَةِ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَأَنَّ مُحَمَّدًا رَسُولُ اللَّهِ ، وَإِقَامِ الصَّلَاةِ ، وَإِيتَاءِ الزَّكَاةِ ، وَالسَّمْعِ ، وَالطَّاعَةِ ، وَالنُّصْحِ لِكُلِّ مُسْلِمٍ " .
Narrated Jarir: I have given a pledge of allegiance to Allah's Apostle for to testify that None has the right to be worshipped but Allah, and Muhammad is His Apostle, to offer prayers perfectly, to pay Zakat, to listen to and obey (Allah's and His Prophet's orders), and to give good advice to every Muslim.
Hadith Reference Sahih Bukhari / The Book of Sales (Bargains) / Hadith: 2157
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة
Hadith 2158
حَدَّثَنَا الصَّلْتُ بْنُ مُحَمَّدٍ ، حَدَّثَنَا عَبْدُ الْوَاحِدِ ، حَدَّثَنَا مَعْمَرٌ ، عَنْ عَبْدِ اللَّهِ بْنِ طَاوُسٍ ، عَنْ أَبِيهِ ، عَنِ ابْنِ عَبَّاسٍ رَضِيَ اللَّهُ عَنْهُ ، قَالَ : قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ : " لَا تَلَقَّوْا الرُّكْبَانَ ، وَلَا يَبِيعُ حَاضِرٌ لِبَادٍ " ، قَالَ : فَقُلْتُ لِابْنِ عَبَّاسٍ : مَا قَوْلُهُ لَا يَبِيعُ حَاضِرٌ لِبَادٍ ؟ قَالَ : لَا يَكُونُ لَهُ سِمْسَارًا .
Narrated Tawus: Ibn `Abbas said, "Allah's Apostle said, 'Do not go to meet the caravans on the way (for buying their goods without letting them know the market price); a town dweller should not sell the goods of a desert dweller on behalf of the latter.' I asked Ibn `Abbas, 'What does he mean by not selling the goods of a desert dweller by a town dweller?' He said, 'He should not become his broker.' "
Hadith Reference Sahih Bukhari / The Book of Sales (Bargains) / Hadith: 2158
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة