Maliks Muwatta Book 051, Hadith Number 006.

Section : Caring for the Hair.

Yahya related to me from Malik from Yahya ibn Said that Abu Qatada al-Ansari said to the Messenger of Allah, may Allah bless him and grant him peace, "I have a lot of hair which comes down to my shoulders, shall I comb it?'' The Messenger of Allah. may Allah bless him and grant him peace, said, "Yes, and honour it." Sometimes Abu Qatada oiled it twice in one day because the Messenger of Allah, may Allah bless him and grant him peace, said to him. "Honour it."