Mahmud bin Ghaylan محمود بن غيلان العدوي مولاهم أبو أحمد · The Book of the Commencement of the Prayer

Abdullah saw a man who was praying with his feet together. He said: "He is going against the Sunnah; if he shifted his weight from one to the other that would be better."

"The Messenger of Allah (ﷺ) said: 'The Imam is appointed to be followed, so when he says the takbir, say the takbir, and when he recites, be silent.'"