Hazrat Aisha (Radiallahu anha) says, "I used to comb the hair of Sayyidina Rasulullah (Sallallahu alaihe wasallam), even when I was in the state of menstruation." (ID)
English reference (ID): Book 4, Hadith 31 (ID)
Arabic reference (ID): Book 4, Hadith 32 (ID)