The Book of Prayers (Kitab Al-Salat)
Muslim :: Book 4 : Hadith 831
Abu Huraira reported Allah's Messenger (may peace be upon him) saying: The Imamis appointed to be followed. So recite takbir when he recites it, and bow down when he bows down and when he utters:" Allah listens to him who praises Him," say" O Allah, our Lordfor Thee be the praise." And when he prays, standing, you should pray standing. And when he prays sitting, all of you should pray sitting.
Source materials are from the University of Southern California MSA site|
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