It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: No townsman should sell the goods of a villager; do not deceive in trade; no man should bid over his brother's sale; no man should send a marriage proposal over his brother's proposal; and no woman should demand the divorce of her sister (whether real or religious sister).
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 7700