Mishkat al-Masabih #404

‘A'isha said that a woman of the Ansar asked the Prophet about washing after menstruation and he instructed her how to do it, saying, “Take a piece of cotton with musk and purify yourself with it.” She asked how she should do this, and he replied, “Purify yourself with it.” She asked again how she should do this and he replied, “Praise be to God! Purify yourself with it.” ‘A'isha then drew her aside and said, “Go over the mark of the blood with it.” (Bukhari and Muslim.)