Is it obligatory to alert the imam if he adds a rak'ah, when the person is not a ma'mum?

The questioner : If a person who is not a ma'mum knows that the one praying has added a rak'ah. For example, a man is praying next to you and he stands up for a fifth rak'ah, and he is not your imam. Is it obligatory for you to alert him?

The Shaykh : It is obligatory that we alert him. This is one of the two opinions in this matter. The second opinion is that it is not obligatory. Is there a detailed opinion on this? Yes, what?

The presenter : Present the criteria to us.

The Shaykh : Okay. Okay, I am with you. The apparent statement of the jurists is that it is not obligatory for him if he is not an imam, because there is no connection between him and his prayer. But if we return to the generality of the saying of Allah the Exalted , we ask: Is it part of righteousness for the imam to return from the added rak'ah or not? Okay, is reminding him part of cooperation? It is part of cooperation. And for this reason, the correct opinion in my view is that it is obligatory to alert you.