An Nasai: Hadith 3251

It was narrated that Abu Hurairah said: "The Messenger of Allah said: 'Do not artificially inflate prices, a resident should not sell for a Bedouin, a man should not offer more for something that has already been bought by his brother, no one should propose marriage to a woman when someone else has already proposed to her, and no woman should try to bring about the divorce of her sister, in order to deprive her of the blessings that she has.'"