Muwatta Malik, Book 5, Hadith 6 (USC-MSA) ⓘ
Yahya related to me from Malik from Abu'z Zinad from al-Araj from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, "Even saying to your companion 'Listen' while the imam is giving the khutba on the day of jumua, is to speak foolishly."
حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا قُلْتَ لِصَاحِبِكَ أَنْصِتْ وَالإِمَامُ يَخْطُبُ يَوْمَ الْجُمُعَةِ فَقَدْ لَغَوْتَ " .
also referenced under: Book 5, Hadith 231 (In-Book)