Sahih Muslim Book: 17, Hadith: 3521

وَحَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، وَمُحَمَّدُ بْنُ الْمُثَنَّى، جَمِيعًا عَنْ يَحْيَى الْقَطَّانِ، قَالَ زُهَيْرٌ حَدَّثَنَا يَحْيَى، عَنْ عُبَيْدِ اللَّهِ، أَخْبَرَنِي نَافِعٌ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ “‏ لاَ يَبِعِ الرَّجُلُ عَلَى بَيْعِ أَخِيهِ وَلاَ يَخْطُبْ عَلَى خِطْبَةِ أَخِيهِ إِلاَّ أَنْ يَأْذَنَ لَهُ ‏”‏ ‏.‏ Ibn Umar (Allah be pleased with them) reported Allah’s Apostle (may peace be upon him) as having said this:A person should not enter into a transaction when his brother (had already entered into but not finalised), and he should not make proposal of marriage upon the proposal already made by his brother, until he permits it. Chain : Zuhayr bin Harb – Muhammad bin al-Muthna – al-Zaman – Yahya bin Sa’id bin Farroukh al-Qatan – Zuhayr bin Mua’wiya bin Hudayj – Yahya bin Abi Kathir – ‘Ubaidullah bin ‘Umar bin Hafs – Nafie’ – ibn Umar Data Source...