“Whoever leads a people in Salah (prayer) must sit down after the phrase of offering greeting of peace and must not leave that place until those behind him complete (their Salah (prayer)) which is completed after (the Salah (prayer) of the Imam). It is obligatory for every Imam if they know that there are people who have not completed their Salah (prayer). When he finds out that everyone has completed and no one is left he then can go wherever he wants.’” (Ahadith 1 and 2 are best explained in the form of fatwa.)