The Messenger of Allah ﷺ said: "Whoever says to his companion on Friday, when the imam is delivering the khutbah: 'Listen attentively,' has engaged in idle talk." (Using translation from Nasāʾī 1401)
عَنِ النَّبِيِّ ﷺ قَالَ «مَنْ قَالَ لِصَاحِبِهِ يَوْمَ الْجُمُعَةِ وَالْإِمَامُ يَخْطُبُ أَنْصِتْ فَقَدْ لَغَا»