What is the correct way for a person afflicted with obsessive-compulsive disorder (waswas) concerning purity and prayer to form the intention? Is it permissible for her to visualize the intention as a written word or to repeat it in her heart while feeling a sense of strangeness? Is delaying or missing some prayers due to this waswas and effort considered disbelief (kufr) or does it necessitate making up the prayers, knowing that she is aware of the treatment but without success in applying it?

The whisperings (waswas) have reached a great extent within you. Their cure lies in striving to repel these whisperings, not going along with them, and completely turning away from them.

The matter of intention (niyyah) is easier than you imagine, for every legally responsible person who performs an action cannot conceive of that action being devoid of intention. It suffices for you to bring to mind the intention for prayer for just one moment.

As for the prayers that you delayed due to these whisperings until their time expired, we hope that Allah will forgive you and overlook that action of yours, because you are in the position of one who is compelled. We ask Allah to deliver you from this widespread evil.