Sahih Muslim 2338aBook 43, Hadith 125
حَدَّثَنَا شَيْبَانُ بْنُ فَرُّوخَ، حَدَّثَنَا جَرِيرُ بْنُ حَازِمٍ، حَدَّثَنَا قَتَادَةُ، قَالَ قُلْتُ لأَنَسِ بْنِ مَالِكٍ كَيْفَ كَانَ شَعَرُ رَسُولِ اللَّهِ صلى الله عليه وسلم قَالَ كَانَ شَعَرًا رَجِلاً لَيْسَ بِالْجَعْدِ وَلاَ السَّبِطِ بَيْنَ أُذُنَيْهِ وَعَاتِقِهِ .
I asked Anas b. Malik: How was the hair of Allah's Messenger (ﷺ)? Thereupon he said: His hair was neither very curly nor very straight, and they hung over his shoulders and earlobes.