What is the ruling on repeating the middle or final Tashahhud, or Al-Fatiha, or any additional verbal supplication such as "Rabbi ighfir li" (My Lord, forgive me) after rising from the second prostration, whether that is due to doubt, forgetfulness, or intention, and does this necessitate sujood al-sahw (prostration of forgetfulness)?

If a worshipper intentionally repeats the middle or final tashahhud, or Al-Fatihah, their prayer is valid and they are not required to perform the prostration of forgetfulness (sujud al-sahw). If the repetition was due to forgetfulness or doubt, then similarly, sujud al-sahw is not required for the tashahhud. As for Al-Fatihah, sujud al-sahw is legislated by some scholars in this case. Regarding the intentional addition of other spoken acts from the category of prayer adhkar, this does not invalidate the prayer nor is sujud al-sahw legislated for it. If such an addition was due to forgetfulness, there is a difference of opinion among scholars regarding the permissibility of sujud al-sahw for it. If its permissibility is affirmed, it is recommended, not obligatory. It is advised not to pay attention to waswas (whispers of Satan/obsessive thoughts).