Hadith 3919
Narrated Anas: (the servant of the Prophet) When the Prophet arrived (at Medina), there was not a single companion of the Prophet 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).
Hadith 5532
Narrated Ibn `Abbas: The Prophet passed by a dead goat and said, "There is no harm if its owners benefit from its skin."