Is Sujud Al-Sahw (prostration of forgetfulness) obligatory when one forgets the number of times of Tasbeeh (glorification) in Rukoo' (bowing) and Sujud (prostration), and when should it be performed during the prayer, and is anything required after it, and is the prayer valid in this case?

1. Glorifying Allah once during bowing (rukūʿ) and prostration (sujūd) is obligatory. Any additional glorification is sunnah (recommended). The prostration of forgetfulness (sujūd as-sahw) is not prescribed for omitting it or for limiting it to one instance.

2. The prostration of forgetfulness is permissible either before or after the salām (final greeting of peace). It is performed before the salām for omitting an obligatory act or for doubt when building upon the lesser number of rakʿahs. It is performed after the salām for an addition to the prayer or for doubt when one side of the doubt is more likely.

3. The prostration of forgetfulness occurs after the tashahhud (testification of faith). The worshiper then says "Allahu Akbar" (God is Greatest) to rise from it, and then performs the salām. No other remembrance, tashahhud, or supplication is prescribed after it.