How can we help a sister afflicted with obsessive-compulsive disorder (OCD) which prevents her from praying due to her constant feeling of impurity?

We advise that the sister be presented to one of the righteous shaykhs who treat with the Quran and legal ruqyah. She should not surrender to detestable whispers, and abandoning prayer because of them is a great evil. This is what Satan desires, to turn people away from the religion of Allah, for Allah Almighty says: "O you who have believed, do not follow the footsteps of Satan. And whoever follows the footsteps of Satan - indeed, he enjoins immorality and wrongdoing," and His saying, exalted be He: "Indeed, Satan is an enemy to you; so take him as an enemy. He only invites his party to be among the companions of the Blaze." The treatment of whispers has been explained in previous fatwas.