Mishkat al-Masabih 4359
Abu Rimtha at-Taimi said:
When I came to the Prophet he was wearing two green garments, his hair was turning grey, but the grey was dyed red. 
Tirmidhi transmitted it; In a version by Abu Dawud it says he had hanging locks (These locks would hang down as far as the lobes of the ears) stained with henna.
وَعَن أبي رِمْثةَ التيميِّ قَالَ: أَتَيْتُ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَعَلَيْهِ ثَوْبَانِ أَخْضَرَانِ وَلَهُ شَعَرٌ قَدْ عَلَاهُ الشَّيْبُ وَشَيْبُهُ أَحْمَرُ. رَوَاهُ التِّرْمِذِيُّ وَفِي رِوَايَةٍ لِأَبِي دَاوُدَ: وَهُوَ ذُو وَفْرَةٍ وَبِهَا رَدْعٌ من حناء