The imam prayed Maghrib with the people for two rak'ahs, and only some of them noticed; is it obligatory for them to repeat the prayer?

The questioner : Our imam prayed Maghrib for us, and after the prayer was finished, I was walking and did not remember. I am convinced in my mind that he did not pray more than two rak'ahs.

The Shaykh : Praying Maghrib for two rak'ahs.

The questioner : Just two rak'ahs, meaning, and I became certain while I was driving in the car. I am convinced of this because the worshippers were looking at each other, and everyone was saying, "Did he pray or did he not pray?"
And one person said, "Glory be to Allah, he did not complete it," and then he was silent! So, does the prayer need to be repeated, or is he responsible for the prayer of the people?

The Shaykh : No, whoever knows like you must repeat it, or if the interval has not been too long, he should make up the missed rak'ah.

The questioner : I entered the mosque for the 'Isha' prayer, and Abu Malik was there. I said to him, "This is what happened." He is responsible because he, meaning, he took the initiative and became the imam, so I do not know. I had intended to repeat it or make up the rak'ah, and he said, "No, he is responsible."

Another questioner : If he forgot, what is his sin? If it is necessary, you must remind him.

The questioner : Seventy people, a mosque full of people.

The Shaykh : In my opinion, repeating the prayer is necessary if the interval has been long. But if the interval has not been long, it is possible to make up the rak'ah and prostrate twice for forgetfulness, because this occurred during the time of the Messenger of Allah (peace and blessings be upon him). He prayed the Maghrib prayer for two rak'ahs, said the taslim, and the people dispersed. Then it was said to him, "Did you pray two rak'ahs?" So he ordered the iqamah to be called, prayed one rak'ah, and prostrated twice.