It is permissible to offer the five daily prayers individually where there is no congregation. The minimum number of worshippers required for a congregation is two. Where two or more Muslims reside in close proximity to each other, it is recommended that the obligatory prayers be offered in congregation. Congregational prayers are led by an imam who usually stands a little ahead of the front row. The rest of the congregation are obligated to follow the imam throughout the service. If during the namaz the imam commits a mistake, any member of the congregation may draw attention to it by gently saying subhanallah (Holy is Allah); but if the imam does not heed this then it is incumbent on the congregation to continue to follow the imam until the end of the namaz.