Sayyiduna Abdullah bin Umar (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "None of you should sell over the sale of his brother, nor should he send a marriage proposal over the proposal of his brother, except with his permission."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10889