Shama-il Tirmidhi Chapter 6, Hadith Number 3 (46).

Jah-dhamah Radiallahu ‘Anha, the wife of Bashir Kha-saasiyyah Radiallahu ‘Anhu says: “I saw Rasulullah Sallallahu ‘Alayhi Wasallam coming out of the house after taking a bath and was stroking (or combing) his hair. There were signs of henna on his mubaarak head.”