The prohibition of the town-dweller selling on behalf of a bedouin
وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا هُشَيْمٌ، عَنْ يُونُسَ، عَنِ ابْنِ سِيرِينَ، عَنْ أَنَسِ، بْنِ مَالِكٍ قَالَ نُهِينَا أَنْ يَبِيعَ، حَاضِرٌ لِبَادٍ . وَإِنْ كَانَ أَخَاهُ أَوْ أَبَاهُ .
Anas b. Malik (Allah be pleased with him) reported: We were forbidden that a townsman should sell for a man of the desert, even if he is his brother or father.