Sahih Muslim Book 3, Hadith Number 583.

Chapter : The menstruating woman is permitted to wash the head of her husband, comb his hair, and her left-over is clean, and one is permitted to recline in her lap and recite the Qur’an.

‘Amra daughter of ‘Abd al-Rahman reported: ‘Aisha, wife of the Apostle of Allah (may peace be upon him) observed: When I was (in I’tikaf), I entered the house for the call of nature, and while passing I inquired after the health of the sick (in the family), and when the Messenger of Allah (may peace be upon him) was (in I’tikaf), he put out his head towards me, while he himself was in the mosque, and I combed his hair; and he did not enter the house except for the call of nature so long as he was In I’tikaf; and Ibn Rumh stated: As long as they (the Prophet and his wives) were among the observers of I’tikaf.