(45) باب هِجْرَةُ النَّبِيِّ صلى الله عليه وسلم وَأَصْحَابِهِ إِلَى الْمَدِينَةِ
Narrated Anas:
(the servant of the Prophet) When the Prophet (ﷺ) arrived (at Medina), there was not a single companion of the Prophet (ﷺ) who had grey and black hair except Abu Bakr, and he dyed his hair with Henna' and Katam (i.e. plants used for dying hair).
Reference: Sahih al-Bukhari 3919
In-book reference: Book 63, Hadith 145
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 5, Book 58, Hadith 257