One who forgets until the imam has said the closing salam and he has not recited the tashahhud

Question:
If a worshipper forgets during the prayer, and the imam says the closing salam while he has not yet said the tashahhud, should he say the closing salam after the imam, or should he delay so that he can say the tashahhud?

Answer:
If the imam says the closing salam and you have not completed the tashahhud, you must complete it, then say the closing salam. You complete the tashahhud and the prayer upon the Prophet (peace and blessings be upon him), then you say the closing salam. If you complete it with the seeking of refuge in Allah from the punishment of the Hellfire, the punishment of the grave, and so on, that is better; because some scholars have said that this seeking of refuge is obligatory. So it is preferable that you complete it, then say the closing salam after that.
You should not be negligent, but you must pay attention to reciting the tahiyyat so that you say the closing salam immediately after your imam. Beware of negligence until your imam says the closing salam while you are distracted. You must strive to recite the tahiyyat, the prayer upon the Prophet (peace and blessings be upon him), and say the supplication before your imam says the closing salam. But if we assume that he said the closing salam and you had not completed it, complete it, then say the closing salam.