وَعَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «لَا يَبِعِ الرَّجُلُ عَلَى بَيْعِ أَخِيهِ وَلَا يَخْطِبْ عَلَى خِطْبَةِ أَخِيهِ إِلَّا أنْ يأذَنَ لَهُ»
He reported God’s Messenger as saying, “One must not offer more than the amount agreed by his brother*, or ask a woman in marriage when his brother has done so, unless he permits him.” *i.e. when the parties have already agreed on a price.
Mishkat al-Masabih 2732, Book 12, Business Transactions, Hadith 88. 1 min read