Sunan an-Nasa'i, Volume 6, Book 48, Hadith 5235 (DarusSalam) ⓘ
It was narrated that Al-Bara' said: "I never saw any long haired man in a Hullah who was more handsome than the Messenger of Allah [SAW], and he had hair that came down to his shoulders."
أَخْبَرَنَا حَاجِبُ بْنُ سُلَيْمَانَ، عَنْ وَكِيعٍ، عَنْ سُفْيَانَ، عَنْ أَبِي إِسْحَاقَ، عَنِ الْبَرَاءِ، قَالَ مَا رَأَيْتُ مِنْ ذِي لِمَّةٍ أَحْسَنَ فِي حُلَّةٍ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم وَلَهُ شَعْرٌ يَضْرِبُ مَنْكِبَيْهِ .
also referenced under: Hadith 5233 (Reference) & Book 48, Hadith 194 (In-Book)