Sunan Abi Dawud, Hadith 2076 ⓘ
Narrated Abdullah ibn Umar: The Prophet said: One of you must not ask a woman in marriage when his brother has done so already, and one of you must not sell (his own goods) when his brother has already sold (his goods) except with his permission.
حَدَّثَنَا الْحَسَنُ بْنُ عَلِيٍّ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ نُمَيْرٍ، عَنْ عُبَيْدِ اللَّهِ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ يَخْطُبُ أَحَدُكُمْ عَلَى خِطْبَةِ أَخِيهِ وَلاَ يَبِيعُ عَلَى بَيْعِ أَخِيهِ إِلاَّ بِإِذْنِهِ " .
also referenced under: Hadith 2081 (DarusSalam) & Book 11, Hadith 2076 (USC-MSA)