Sunan an-Nasa'i, Hadith 5061 ⓘ
It was narrated that Anas said: "The hair of the Messenger of Allah [SAW] came halfway down his ears."
أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ أَنْبَأَنَا عَبْدُ الرَّزَّاقِ، قَالَ حَدَّثَنَا مَعْمَرٌ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ، قَالَ كَانَ شَعْرُ رَسُولِ اللَّهِ صلى الله عليه وسلم إِلَى أَنْصَافِ أُذُنَيْهِ .
also referenced under: Book 48, Hadith 22 (In-Book) & Volume 6, Book 48, Hadith 5064 (DarusSalam)