He did the first sajdah of sujood al-sahw (prostrations for forgetfulness in the prayer), then he remembered that he did not do anything that required sujood al-sahw

What is to be said in the prostration of forgetfulness and the prostration of recitation?

Should a latecomer count an extra rak’ah done with the imam?

Should he take his cue from the person next to him if he is unsure about the number of rak’ahs?

He forgot and said Allaahu akbar instead of Sami’aAllaahu liman hamidah

He said salaam before the end of the prayer by mistake then he started another prayer

The imam sat briefly after the third rak’ah and the people praying behind him alerted him to that; should he do the prostration of forgetfulness?

If the imam stands up for a fifth rak’ah

If a person does not do the obligatory prostration of forgetfulness

The difference between pillars (essential parts) and obligatory parts of prayer