Hadith 534
من تكلم يوم الجمعة والامام يخطب فهو كالحمار يحمل اسفارا والذي يقول له انصت ليس له جمعة
"Whoever speaks during the Friday sermon while the Imam is delivering the khutbah is like a donkey carrying books, and whoever says to him 'Be quiet,' his Friday (prayer) is not valid."
