What Should The Congregation Do If An Imam Stands Up Without Performing The Last Sitting?

What should the congregation do if an imam stands up without performing the last sitting?

If an imam stands up without performing the last sitting by forgetfulness, congregation does not stand up with the imam, continues to recite tashahhud and waits for him to sit back. Meanwhile, “subhanallah” is recited aloud in order to warn the imam. A person who follows an imam cannot give salam and finish the prayer as long as the imam does not perform the prostration of the rakat in which he stood up as there is a possibility for him to go back and perform it . One’s prayer is invalidated if he gives salam in that situation. If the imam does not go back but continues prayer without recognizing his mistake and performs prostration of the rakat for which he stood up, both the prayer of the congregation and of the imam are invalidated as the imam did not perform the last sitting.

If the congregation stands up with the imam and imam sits back without performing prostration by recognizing his mistake, the congregation also sits. If the congregation goes down to prostration without noticing that the imam sat, this prostration does not invalidate their prayer. Because what matters in this situation is the validity of imam’s prayer (Ibn Nujaym, al-Bahr, II, 110).

Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATW