كتاب الفضائل
43  
The Book of Virtues
(25)
Chapter: Description Of The Prophet (SAW); He Was The Most Handsome Of People
(25)
باب فِي صِفَةِ النَّبِيِّ صلى الله عليه وسلم وَأَنَّهُ كَانَ أَحْسَنَ النَّاسِ وَجْهًا ‏.‏
Sahih Muslim 2337 b

Al-Bara' reported:

Never did I see anyone more handsome than Allah's Apostle (ﷺ) in the red mantle. His hair had been hanging down on the shoulders and his shoulders were very broad, and he was neither very tall nor short-statured. Ibn Kuraib said he had hair.
حَدَّثَنَا عَمْرٌو النَّاقِدُ، وَأَبُو كُرَيْبٍ قَالاَ حَدَّثَنَا وَكِيعٌ، عَنْ سُفْيَانَ، عَنْ أَبِي إِسْحَاقَ، عَنِ الْبَرَاءِ، قَالَ مَا رَأَيْتُ مِنْ ذِي لِمَّةٍ أَحْسَنَ فِي حُلَّةٍ حَمْرَاءَ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم شَعْرُهُ يَضْرِبُ مَنْكِبَيْهِ بَعِيدَ مَا بَيْنَ الْمَنْكِبَيْنِ لَيْسَ بِالطَّوِيلِ وَلاَ بِالْقَصِيرِ ‏.‏ قَالَ أَبُو كُرَيْبٍ لَهُ شَعَرٌ ‏.‏
Reference : Sahih Muslim 2337b
In-book reference : Book 43, Hadith 123
USC-MSA web (English) reference : Book 30, Hadith 5771
  (deprecated numbering scheme)