Combing the Hair (Kitab Al-Tarajjul)
Dawud :: Book 33 : Hadith 4196
Narrated AbuRimthah:
I and my father came to the Prophet (peace_be_upon_him). He said to a man or to my father: Who is this? He replied: He is my son. He said: Do not commit a crime on him. He had stained his beard with henna.