Sahih Bukhari Volume 001, Book 006, Hadith Number 295.
Narated By 'Urwa : A person asked me, "Can a woman in menses serve me? And can a Junub woman come close to me?" I replied, "All this is easy for me. All of them can serve me, and there is no harm for any other person to do the same. 'Aisha told me that she used to comb the hair of Allah's Apostle while she was in her menses, and he was in Itikaf (in the mosque). He would bring his head near her in her room and she would comb his hair, while she used to be in her menses."