What is the ruling for a follower (Ma'mum) who rises to make up missed parts of the prayer (Qada') when the Imam performs the prostration of forgetfulness (Sujud As-Sahw) after the Taslim (final greeting)?

Primary text

The ruling for the follower rising to make up missed parts is analogous to the ruling for one who rises from the first Tashahhud. If the Imam performs the prostration of forgetfulness before the follower becomes fully upright, the follower must return to sitting. If the follower becomes fully upright but has not yet begun reciting (the missed parts), they are not required to return, although returning would be permissible. If the follower has already begun reciting, they may not return to sitting. This position is explicitly stated by Ahmad. The reasoning is that rising to make up missed obligatory parts is analogous to rising from the first Tashahhud, which is a transition from an obligation to a pillar (Rukn).