Is keeping white/grey hair/beard haram?

I would like to extend this question (unanswered) I read here that, > “The Jews and the Christians do not dye their hair, so be different > from them.” (Narrated by al-Bukhaari, 3275; Muslim, 2103). > > إِنَّ الْيَهُودَ وَالنَّصَارَى لاَ يَصْبُغُونَ، فَخَالِفُوهُمْ So is keeping grey/white hair not permissible in Islam ? I couldn't find any more references.