What is the criterion for debilitating doubt and obsessive whispering, and must one ignore the obsessive whispering that occurs in all acts of worship and causes the repetition of prayers and the recitation of the Quran?

The cure for the whispers of doubt (waswas) is to cast them aside and pay no attention to them. So, whoever doubts the validity of his ablution (wudu') should consider it valid, and whoever doubts the number of prostrations (rak'ats) should take the higher number. The recurring doubt is that which comes every day, even if only once, whether concerning a specific matter or various matters related to prayer. One must cast it aside, disregard it, and build upon the higher number. It is recommended to prostrate after the salutation (taslim) to spite Satan.