Depends why the therapist is suggesting it. If he thinks that praying in and of itself will be valuable, eg, because the patient is religious and a calm, focus

Depends why the therapist is suggesting it. If he thinks that praying in and of itself will be valuable, eg, because the patient is religious and a calm, focussed mental state would be valuable, then it is good therapy. If the therapist is suggesting that the patient ask God to cure him... well, that's not good therapy.