Is the prostration of forgetfulness (sujud al-sahw) obligatory for someone who mistakenly said "Subhan Rabbi al-A'la" (Glory be to my Lord, the Most High) instead of "Subhan Rabbi al-Adheem" (Glory be to my Lord, the Most Magnificent) in rukoo' (bowing), and vice-versa in sujud (prostration), and should it be before or after the salaam (final salutation)?

If someone forgets and says, "Subhana Rabbiyal-A'la (Glory to my Lord, the Most High)" during bowing (ruku'), or "Subhana Rabbiyal-Azeem (Glory to my Lord, the Almighty)" during prostration (sujood), there are two scenarios:

1. If they remember before rising: They should say the correct dhikr (remembrance) in its proper place. Sujood as-sahw (prostration of forgetfulness) is not obligatory for them, but it is recommended because they recited a dhikr in the wrong place. 2. If they remember after rising: Sujood as-sahw is obligatory for them before the tasleem (salutation) because they omitted an obligation.

If the worshipper is a follower (ma'mum) and commits a mistake, then if they joined the prayer from the beginning, there is no sujood as-sahw for them (the Imam bears it on their behalf). If they were a latecomer (masbuq), they should perform sujood as-sahw at the end of their prayer, whether their mistake occurred with the Imam or after they stood up to complete what they missed. If the follower commits a mistake that invalidates a rak'ah (such as forgetting Al-Fatiha), they should stand up after the Imam's tasleem, perform the rak'ah, then recite the tashahhud (definition), perform the tasleem, and then perform sujood after the tasleem.