ENOfficial
It was narrated from Ibn Umar that: the Messenger of Allah (ﷺ) said: “A man should not propose to a woman to whom his brother has already proposed.”
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا يَحْيَى بْنُ حَكِيمٍ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " لاَ يَخْطُبِ الرَّجُلُ عَلَى خِطْبَةِ أَخِيهِ " .
sunnah.com