Translation
(9) The Chapters on Marriage
كتاب النكاح
(10) Chapter: A man should not propose marriage to a woman to whom his brother already proposed
(10) باب لاَ يَخْطُبِ الرَّجُلُ عَلَى خِطْبَةِ أَخِيهِ
Sunan Ibn Majah 1867 
It was narrated from Abu Hurairah that:
the Messenger of Allah said: “A man should not propose to a woman to whom his brother has already proposed.”
حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، وَسَهْلُ بْنُ أَبِي سَهْلٍ، قَالاَ حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏ "‏ لاَ يَخْطُبِ الرَّجُلُ عَلَى خِطْبَةِ أَخِيهِ ‏"‏ ‏.‏
Grade :  Sahih (Darussalam)
Reference : Sunan Ibn Majah 1867
In-book reference : Book 9, Hadith 23
English translation : Vol. 3, Book 9, Hadith 1867