The ruling on following the imam if he makes a mistake in the first tashahhud
Machine translationRead the Arabic original
Question:
Then this questioner says: I entered the mosque with the congregation for the Maghrib prayer, but I missed the first rak'ah. I joined them in the row, but when the imam reached the first tashahhud, he said the taslim without standing up for the third rak'ah. So I stood up and completed my prayer alone. What should I do in that situation? Do I follow the imam until he makes a mistake and I prostrate with him for sujud al-sahw, or do I complete the prayer alone?
Answer:
No, wait until the imam stands up. Alert the congregation, wait until the imam is alerted or you alert him by saying "Subhan Allah." When he stands up, you stand up with him and complete your prayer with him. When he says the taslim, you stand up and make up what you missed.
Then this questioner says: I entered the mosque with the congregation for the Maghrib prayer, but I missed the first rak'ah. I joined them in the row, but when the imam reached the first tashahhud, he said the taslim without standing up for the third rak'ah. So I stood up and completed my prayer alone. What should I do in that situation? Do I follow the imam until he makes a mistake and I prostrate with him for sujud al-sahw, or do I complete the prayer alone?
Answer:
No, wait until the imam stands up. Alert the congregation, wait until the imam is alerted or you alert him by saying "Subhan Allah." When he stands up, you stand up with him and complete your prayer with him. When he says the taslim, you stand up and make up what you missed.
Source
المسبوق وما يفعله تجاه سهو الإمام — alfawzan.live
The Arabic text is a machine transcription of the audio recording.