If the latecomer arrives while the imam is in the tashahhud, should he pray with him or pray with the second congregation?

The questioner:
Please, Abdullah from Bisha, please come on the line. Peace be upon you. And upon you be peace. How are you, Shaykh?

The Shaykh:
May Allah welcome you. I bear witness to Allah that I love you. Honorable Shaykh. May Allah welcome you, may Allah love you.

The questioner:
O dear one, I was asking you, O dear one, whenever I am late for the imam in prayer, do I pray with him? If I stand up, I stand up for the rak'ah during the taslim, or immediately after the taslim?

The Shaykh:
Yes.

The questioner:
If one is late for the prayer and the imam has already said the taslim, does he wait, or does he stand up before the imam says the taslim?

The Shaykh:
If he knows that a group will be coming, he waits for them. But if he does not know whether anyone will come or not, he joins the imam in whatever remains of the prayer to obtain the reward of following the imam. Yes.