Sometimes, it is possible that a person doubts over performing a part of their prayers, for example, they doubt whether they have pronounced Tashahud, or doubt whether they have performed one prostration or two, and at times this doubt is aroused over the number of the Rak'ats one has been offering, for instance, they doubt whether they are offering the third Rak'at or the fourth.
Regarding such doubts, there are special laws and it is not possible to list and explain them all here; however, a brief explanation on the kinds of doubt and the corresponding rules comes below:
Translator’s Preface
سائٹ کي سروسز
تفکر
