What is the ruling on someone who caught the entire prayer with the Imam, and the Imam made a mistake and performed the prostration of forgetfulness (sujud al-sahw) after the final tashahhud and before the taslim (salaam), and the worshiper (ma'mum) did not catch the first prostration and the sitting between the two prostrations of the prostration of forgetfulness because he was completing the final tashahhud?

If the Imam performs the prostration of forgetfulness (sujud al-sahw), the congregant (ma'mum) must follow him, as the Prophet, peace and blessings be upon him, said: "Indeed, the Imam is appointed to be followed. So when he prostrates, then prostrate." If the congregant is in the final tashahhud when the Imam performs the prostration of forgetfulness, he should complete his tashahhud, then join the Imam and prostrate with him. If the congregant only performs one prostration, he must repeat the prayer. However, if he performs two prostrations, he does not need to repeat the prayer.