I forgot the prayer upon the Messenger in the final tashahhud and did not notice until after I had said the taslim with the imam. What is required of me?

Question:
He says: Honorable Shaykh, I seek Allah's forgiveness from you. He says: I prayed the Zuhr prayer and forgot the prayer upon the Prophet (peace and blessings be upon him) in the final tashahhud, and I did not notice until after I had said the taslim with the imam. What is required of me? And do I repeat the prayer?

Answer:
You return after the imam. You return after you have said the taslim. You return to the prayer. You perform the prayer upon the Prophet (peace and blessings be upon him), then you say the taslim. Yes.