The Messenger of Allah ﷺ said, "A man must not propose marriage over the proposal of his brother."
حدثنا يحيى بن حكيم حدثنا يحيى بن سعيد عن عبيد الله بن عمر عن نافع
قال رسول الله ﷺ لا يخطب الرجل على خطبة أخيه
Muslim narrated it, in the Book of Marriage, the previous chapter, no. 1412, from the hadith of Yahya, through him, and in the Book of Trade, the chapter on the prohibition of a man outbidding his brother's sale... etc, no. 8/1412.