Anas (may Allah be pleased with him) said: The Messenger of Allah ﷺ forbade that a town-dweller sell on behalf of a desert-dweller, even if he were his brother by his father and mother. Agreed upon.
٣٥٥ - باب تحريم بيع الحاضر للبادي وتلقي الركبان، والبيع على بيع أخيه والخطبة على خطبته إلا أن يأذن أو يرد
Anas (may Allah be pleased with him) said: The Messenger of Allah ﷺ forbade that a town-dweller sell on behalf of a desert-dweller, even if he were his brother by his father and mother. Agreed upon.
Ibn ʿUmar (may Allah be pleased with them both) said: The Messenger of Allah ﷺ said: “Do not go out to meet the goods [of incoming traders] until they are brought down into the markets.” Agreed upon.
Ibn ʿAbbās (may Allah be pleased with them both) said: The Messenger of Allah ﷺ said: “Do not go out to meet the riders [bringing goods], and let no town-dweller sell on behalf of a desert-dweller.” Ṭāwūs said to him [Ibn ʿAbbās]: “What does ‘a town-dweller should not sell for a desert-dweller’ mean?” He said: “He should not act as a broker for him.” Agreed upon.
Abū Hurayrah (may Allah be pleased with him) said: The Messenger of Allah ﷺ forbade that a town-dweller sell on behalf of a desert-dweller; and [he said]: “Do not artificially inflate prices in bidding, let no man sell against the sale of his brother, let none propose marriage over the proposal of his brother, and let no woman ask for the divorce of her sister [co-wife] so as to empty what is in her vessel [i.e. take her place].” In another narration he said: The Messenger of Allah ﷺ forbade going out to meet [incoming traders], that a townsman (lit. emigrant) buy on behalf of a Bedouin, that a woman stipulate the divorce of her sister, and that a man bargain over the bargaining of his brother; and he forbade najsh (false bidding) and taṣriyah (withholding an animal’s milk to deceive). Agreed upon.
Ibn ʿUmar (may Allah be pleased with them both) reported that the Messenger of Allah ﷺ said: “Let none of you sell against the sale of another, and let no one propose marriage over the proposal of his brother, unless he gives him permission.” Agreed upon, and this is the wording of Muslim.
ʿUqbah ibn ʿĀmir (may Allah be pleased with him) reported that the Messenger of Allah ﷺ said: “The believer is the brother of the believer, so it is not lawful for a believer to buy against the sale of his brother, nor to propose marriage over the proposal of his brother until he gives it up.” Narrated by Muslim.