Sayyiduna Imran bin Husayn (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) forbade jalab and janab.
And he forbade lams and najsh in buying and selling.
And he forbade that a man should sell over the sale of his brother, or propose marriage over the proposal of his brother.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15697