كتاب النكاح
16
The Book of Marriage
(6)
Chapter: The prohibition of proposing marriage when one's brother has already proposed, unless he gives permission or gives up the idea
(6)
باب تَحْرِيمِ الْخِطْبَةِ عَلَى خِطْبَةِ أَخِيهِ حَتَّى يَأْذَنَ أَوْ يَتْرُكَ ‏‏
Sahih Muslim 1412 c
Narrated Ibn Umar :
The above hadith has been narrated by Ibn Umar through another chain.
وَحَدَّثَنَاهُ أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، عَنْ عُبَيْدِ اللَّهِ، بِهَذَا الإِسْنَادِ.
Reference : Sahih Muslim 1412 c
In-book reference : Book 16, Hadith 59
USC-MSA web (English) reference : Book 8, Hadith 3287
  (deprecated numbering scheme)