Sahih Muslim | Book 8 | Hadith Number 3289

Narrated by Abu Huraira (Allah be pleased with him)
Abu Huraira (Allah be pleased with him) reported Allah's Apostle (may peace be upon him) as having forbidden a dweller of the town selling the merchandise of a villager or outbidding in a sale (in order that another might fall into a snare), or a person making the proposal of marriage when his brother has already made such a proposal, or entering into a transaction when his brother has already entered; and a woman asking the divorce of her sister in order to deprive her of what belongs to her. 'Amr made this addition: "The person should not purchase in opposition to his brother.