The Prophet (ﷺ) said, "The Imam is (appointed) to be followed. So do not differ from him, bow when hebows, and say, "Rabbana-lakal hamd" if he says "Sami`a l-lahu liman hamidah"; and if he prostrates,prostrate (after him), and if he prays sitting, pray sitting all together, and straighten the rows for theprayer, as the straightening of the rows is amongst those things which make your prayer a correct andperfect one.