The ruling for one who joins the prayer late if the imam prostrates for forgetfulness after the closing salam

Question:
The imam prostrated for forgetfulness after the closing salam. What is required of the one who missed a unit of prayer? Does he say the closing salam with the imam and then prostrate?

Answer:
No, he says the closing salam when he has made up what is required of him, and then he prostrates. So, the one who joins the prayer late, when he has made up what is required of him, prostrates for forgetfulness. This applies if he said the closing salam with the imam in error, or if he made a mistake in the part of the prayer he performed alone, whether he made the mistake while following his imam or in the part he performed on his own. His prostration is two prostrations, performed after he has completed his prayer and before he says the closing salam.