The Messenger of Allah ﷺ forbade that a town-dweller sell on behalf of a desert-dweller, and that you inflate prices through false bidding, and that a man buy over his brother's purchase, and that he propose over his brother's proposal, and that a woman ask for the divorce of her sister so as to empty what is in her vessel.
نهي رسول الله ﷺ أن يبيع حاضر لباد، ولا تناجشوا، ولا يبيع الرجل على بيع أخيه، ولا يخطب على خطبة أخيه، ولا تسأل المرأة طلاق أختها لتكفأ ما في إنائها.
Bukhari related it in the Book of Sales (2140), and Muslim in the Book of Sales (1413), both from the hadith of Sufyan bin Uyayna, from Zuhri, from Saeed bin Musayab, from Abu Hurairah, who mentioned it.