What is the ruling on the prayer of the followers who prayed behind the imam intending the midday prayer, while he prayed with them intending the afternoon prayer?

The questioner : A person entered and joined an imam who was praying with a group of worshippers. It was the time for the midday prayer, but the imam thought it was the time for the afternoon prayer, so he began praying the afternoon prayer.

The Shaykh : Who thought that?

The questioner : The imam.

The Shaykh : I mean the imam.

The questioner : Intending the afternoon prayer.

The Shaykh : While it was the time for the midday prayer.

The questioner : Yes, so what is the ruling on the prayer of the follower who intended the midday prayer?

The Shaykh : The prayer of the follower who intended the midday prayer is valid, but the imam has to repeat it.

The questioner : Yes, one last question, if you would be so kind.

The Shaykh: Yes.