Hadith 1112
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 (ﷺ) 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.
Reference : Sunan Abi Dawud 1112
In-book reference : Book 2, Hadith 723