Sahih Bukhari – Volume 1 – Book 6 – P.207

296:  Narrated ‘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.  ‘Aishah told me that she used to comb the hair of Allah’s Messenger, peace be upon him, while she was in her menses, and he was in I’tikaf1 (in the mosque).  He would bring his head near her room and she would comb his hair, while she used to be in her menses.”

1I’tikaf: Seclusion in a masjid for the purpose of worshipping Allah only.  The one in such a state should not have sexual relations with his wife, and one is not allowed to leave the masjid except for a very short period, and that is only for very urgent necessity, e.g. answering the call of nature or joining a funeral procession etc