Mishkat al-Masabih 4460
‘A’isha said :
God’s messenger and I used to wash from one vessel; and he had hair which did not reach the shoulder but which came lower than the ear. 
Tirmidhi transmitted it.
وَعَنْ عَائِشَةَ قَالَتْ: كُنْتُ أَغْتَسِلُ أَنَا وَرَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مِنْ إِنَاءٍ وَاحِدٍ وَكَانَ لَهُ شَعْرٌ فَوْقَ الْجُمَّةِ وَدُونَ الوفرة. رَوَاهُ التِّرْمِذِيّ وَالنَّسَائِيّ