حَدَّثَنَا الْقَعْنَبِيُّ، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، عَنْ سَعِيدٍ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ إِذَا قُلْتَ أَنْصِتْ وَالإِمَامُ يَخْطُبُ فَقَدْ لَغَوْتَ ‏"‏ ‏.‏

Abu Hurairah reported the Messenger of Allah (PBUH) as saying: When you tell (your brother on Friday) to be silent while the imam is giving the sermon you are guilty of idle talk. Translation Not Available

Book Ref: Sunan Abi Dawud Book 2 Hadith 1112
Web Ref:  Sunan Abi Dawud Book 2 Hadith 1107