Ash-Shama'il Al-Muhammadiyah, Book 3, Hadith 24 (English) ⓘ

Ayesha R.A. reported: Rasulullah and I bathed in one utensil, and the mubarak hair of Rasulullah was longer than those that reached the ear lobes, and were less than those that reached the shoulders". (It means that they were not very long nor were they short, but of a medium length).

حَدَّثَنَا هَنَّادُ بْنُ السَّرِيِّ، قَالَ‏:‏ أَخْبَرَنَا عَبْدُ الرَّحْمَنِ بْنُ أَبِي الزِّنَادِ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ‏:‏ كُنْتُ أَغْتَسِلُ أَنَا وَرَسُولُ اللهِ صلى الله عليه وسلم مِنْ إِنَاءٍ وَاحِدٍ، وَكَانَ لَهُ شَعَرٌ فَوْقَ الْجُمَّةِ، وَدُونَ الْوَفْرَةِ‏.‏