What is required of one who doubts the number of rak'ahs?

Question:
If a man stands in his prayer and prays two rak'ahs, for example, and while in the third rak'ah doubt enters him and he does not know whether he recited al-Fatihah in the second rak'ah or not, and neither possibility is more likely in his mind, knowing that this has happened to him repeatedly, what is required of him in this?

Answer:
If the waswas (whispers) are repeated, he should not pay attention to them, and he should assume that he recited it, in order to frustrate Shaytan. However, if it is something incidental and not repeated, this invalidates it, and the third rak'ah becomes a substitute for it, and he performs an extra rak'ah and prostrates for forgetfulness. But if it is repeated waswas, this is from Shaytan, and he should not pay attention to it; he considers it as if it did not happen, does not repeat it, and does not perform anything in its place. Yes.

The presenter: May Allah reward you with good.