The Book of Adornment
48/9. Chapter:
Letting the Hair Grow
Sunan an-Nasai
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 .
It was narrated that Anas said: "The hair of the Messenger of Allah [SAW] came halfway down his ears."
Reference : Sunan an-Nasa'i 5061In-book reference : Book 48, Hadith 22English translation : Vol. 6, Book 48, Hadith 5064