The World Federation One Stop Fiqh

Ruling 1172

If a person doubts excessively about a particular act of the prayer such that his excessive doubting is considered to be only with regard to that particular act, in the event that he has a doubt about another act of the prayer, he must act according to the instructions that apply to a person who is not an excessive doubter. For example, if someone who doubts excessively about whether or not he has performed sajdah also doubts whether he has performed rukūʿ or not, he must act according to the instructions concerning that doubt; i.e. if he has not gone into sajdah, he must perform rukūʿ, and if he has gone into sajdah, he must dismiss his doubt.