سنن النسائي

It was narrated that Hittan bin 'Abdullah said: "Abu Musa led us in prayer and when he was sitting, a man from among the people entered and said: 'Prayer is based on righteousness and is always mentioned alongside Zakah (in the Qur'an).' When Abu Musa had said the Salam, he turned to the people and said: 'Which of you spoke these words?' The people kept quiet. Then he said: 'O Hittan, perhaps you said it?' He said: 'No, but I was afraid that you would rebuke me for it.' He said: 'The Messenger of Allah (ﷺ) taught us our prayer and Sunnah prayers, and he said: The Imam is appointed to be followed, so when he says the Takbir, say the Takbir; when he says "Not (the way) of those who earned Your Anger, nor of those who went astray," say Amin, and Allah will respond to you; when he rises up from bowing and says, 'Sami' Allalhu liman hamidah (Allah hears those who praise Him), say 'Rabbana lakal-hamd (Our Lord, to You be praise),' and Allah will hear you; when he prostrates, prostrate, and when he sits up, sit up. The Imam should prostrate before you do and sit up before you do.' The Messenger of Allah (ﷺ) said: 'This makes up for that.'"