Anas bin Malik RA reports:
"I did not count more than fourteen (strands of) white hair on the head and beard of Rasulullah (SAW)."
Rasulullah SAW had very few white hair. In this narration, fourteen strands of hairs have been mentioned. Other narrations describe the amount to be seventeen, eighteen, and in some narrations - twenty strands of white hairs have been mentioned. There is no contradiction in this as the other Ahadith may have been related during different periods throughout the lifetime of Rasulullah SAW. Also, a difference in counting may also be possible.