The Prophet ﷺ forbade a town-dweller from selling on behalf of a desert-dweller.
إن النبي ﷺ نهي أن يبيع حاضر لباد.
Abu Dawud (3441) narrated it from Musa bin Ismail, who said, Hammad related to us, from Muhammad bin Ishaq, from Salim Makki, that a bedouin told him that he came with a she-camel of his for milking during the time of the Messenger of Allah ﷺ, and stayed at the home of Talha bin Ubaydullah. Talha said, "The Prophet ﷺ forbade that a settled person should sell on behalf of a bedouin. But go to the market and see who will trade with you, then consult me so that I may direct you or advise against it."Its chain of transmission is hasan because of Muhammad bin Ishaq, who is a mudallis, though he has explicitly stated "related to me" in the version at Imam Ahmad (1404), in a longer account than this one. This has already been documented in the book on zakat, in the section on not overstepping in dealings related to charitable funds. Salim Makki is Salim bin Abu Umaya, Abu Nadr, as is explicitly stated in Musnad Ahmad.On this subject there is also what was narrated from Ibn Abu Yazid, that the Messenger of Allah ﷺ said, "Leave people to benefit from one another. But if one of you is asked for sincere advice by his brother, let him give it sincerely." This was narrated by Ahmad (15455), Tabarani in Al-Kabir (22/354), and Abd bin Humayd (438), all of them through routes from Ata bin Saaib, from Hakeem bin Abu Yazid, from his father, who said, my father related to me that the Messenger of Allah ﷺ said, and then he related the hadith.Hakeem bin Abu Yazid was not deemed reliable by anyone except Ibn Hibban. There is also disagreement as to whether the chain is Hakeem bin Abu Yazid, from his father, from his grandfather, as it appears in Ahmad's version, or Hakeem bin Abu Yazid, from his father, as it appears elsewhere, without mention of his grandfather. Ibn Hajar pointed to this disagreement in Al-Isabah, in the biographical entry on Abu Yazid. The one who narrated from him, Ata bin Saaib, suffered a decline in memory late in life, and everyone who transmitted this hadith from him did so after that decline had set in. Haythami identified this as the flaw in Al-Majmu (4/83).Most scholars of knowledge have disapproved of a settled person selling on behalf of a bedouin, taking the prohibition to indicate that it is forbidden, since a settled person selling on behalf of a bedouin undermines the benefit that trading and commerce are meant to serve, namely that Allah provides for people through one another. Some scholars, however, held that the prohibition was meant as guidance rather than as an indication of prohibition.