What is the ruling if one doubts performing a pillar (rukn) while still in the prayer?
Chapter on the Two Prostrations of Forgetfulness
Al-Mughni
Book of Prayer
Primary text
If one doubts whether they omitted a pillar while still engaged in the prayer, the ruling is the same as if they had not performed it, whether they are leading (Imam) or praying alone, because the default state is non-performance (absence).
Supporting text
If one doubts an addition that necessitates the prostration of forgetfulness, no prostration is due, as the default state is the absence of the addition. If one doubts the number of rak'ahs, or a pillar that was remembered during the prayer, no prostration is made, as prostration is for an actual addition, subtraction, or the strong probability thereof, which is not established by mere doubt.