What is the ruling for someone who remembers or doubts a deficit in the number of Rak'ahs during the first Taslim?

If a worshiper doubts a deficiency in prayer before the taslim (salutation), and the doubt occurs before uttering the first taslim, then he must pause and perform what he doubts he missed. Otherwise, his prayer is invalid according to some scholars. However, if the doubt occurs after uttering the first taslim, there is a difference of opinion on the matter:

- According to the majority of scholars, who hold that the prayer is completed with the first taslim, one should not pay attention to doubt thereafter unless one is certain of a deficiency. In that case, he should perform what was missed and prostrate for forgetfulness (sujud al-sahw). If a long time has passed, he must repeat the prayer.

- According to the Hanbalis, who consider the second taslim a pillar, the worshiper has not exited the prayer with the first taslim. Therefore, he must build upon certainty and perform what he doubts he missed, then prostrate for forgetfulness, and this is more cautious. Whoever is certain of a deficiency must perform what he omitted, and if a long time has passed, he must repeat the entire prayer.