Musannaf Ibn Abi Shaybah 7326 — The imam praying sitting

It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The imam is appointed only so that you follow him. When he says the takbir, you say the takbir too; when he recites, you remain silent; when he says 'Ghayri al-maghdubi 'alayhim wa la al-dallin' (not of those who have earned anger, nor of those who go astray), you say Amin. When he bows, you bow; when he says 'Sami'a Allahu liman hamidah' (Allah hears the one who praises Him), you say 'Allahumma Rabbana laka al-hamd' (O Allah, our Lord, to You belongs all praise). When he prostrates, you prostrate, and when he prays sitting, you also pray sitting."