The Messenger of Allah (ﷺ) forbade that a man in the city should be the commission agent of a man from the desert and prohibited the practice of Najsh (i.e., offering a high price for something in order to allure another customer who is interested in the thing); and that a man should make an offer while the offer of his brother is pending; or that he should make a proposal of marriage while that of his brother is pending; or that a woman should try that a sister of hers might be divorced so that she might take her place.

Another narration is: The Messenger of Allah (ﷺ) forbade the people from meeting the caravan on the way for entering into business transaction with them; and the selling of the goods by a dweller of the city on behalf of a man of the desert; and the seeking by a woman the divorce of her sister (from her husband); and the practice of Najsh and leaving the animals unmilked (for sometime for the purpose of accumulation of milk to deceive the buyer).

[Al-Bukhari and Muslim].