Combing the Hair (Kitab Al-Tarajjul)
Dawud :: Book 33 : Hadith 4168
Narrated Ammar ibn Yasir:
The Prophet (peace_be_upon_him) said: The angels do not come near three: the dead body of the unbeliever, one who smears himself with khaluq, and the one who is sexually defiled except that he performs ablution.