Abu Huraira (may Allah be pleased with him) narrates that the Prophet Muhammad (peace and blessings be upon him) said: "Do not practice najsh (deception by bidding to raise the price), no townsman should sell for a villager, no man should make a deal over his (Muslim) brother's deal, no one should propose over his (Muslim) brother's proposal, and no woman should demand the divorce of her (Muslim) sister."