The World Federation One Stop Fiqh

Ruling 1221

There is no difference in the rules for doubt, inadvertence, and supposition in the daily obligatory prayers and the other obligatory prayers. For example, if in ṣalāt al‐āyāt one doubts whether he has performed one rakʿah or two, then as his doubt is in a two rakʿah prayer, his prayer becomes invalid.50 If he has a supposition that he has performed two rakʿahs or that he has performed one rakʿah, he must complete his prayer in accordance with his supposition.

50 See Ruling 1151.