The Ruling on Doubt Regarding the Number of Rak'ahs in Prayer and Obsessive Compulsive Disorder

Question:
May Allah reward you, Your Excellency the Shaykh. The questioner says: Sometimes I doubt the number of rak'ahs in my prayer, so I act on the preponderance of my opinion, I conclude the prayer, and then after the taslim I perform an extra rak'ah and prostrate for forgetfulness as a precaution. Is this action valid, given that I frequently doubt in my prayer?

Answer:
Frequent doubt in your prayer is a matter of waswas (whispers of Satan), not a matter of opinion. This is waswas. Ignore it, ignore it. It is waswas. Leave the waswas alone so that it does not increase upon you, and complete your prayer without turning to the waswas. However, if it is not a matter of waswas, but rather a matter of doubt, there is a difference between waswas and doubt. If it is a matter of doubt, the rule is that you build upon certainty. If you doubt whether you prayed three or four, make it three, perform the fourth, and prostrate for forgetfulness. You build upon certainty. Some scholars say one builds upon the preponderance of his opinion. He builds upon the preponderance of his opinion and prostrates for the distraction. If it is preponderant in his opinion that he prayed four, he builds upon that and concludes the prayer, but he prostrates for the distraction. Yes.