Question:
If the imam gives salaam before a person finishes Tashahhud, Salawat, and Du‘a in the final sitting, should the person follow immediately or complete recitation first?
What about in the first sitting?
Answer:
If Imam finishes before you complete Tashahhud, Salawat, and Du‘a in final sitting:
You may complete them and then give Salaam. Because, after Imam’s Salaam, your link ends. But in the first sitting (2nd rak‘ah): If Imam stands up while you are reciting: You must follow Imam. Do not delay so much that you miss following him.
Imam is appointed to be followed. If he moves ahead, you follow.
If Imam is extremely fast and does not allow you to recite obligatory portions:
You may intend to leave congregation and complete prayer individually.
Because obligatory elements cannot be neglected.